Refactor construction of application objects

- Use a builder and make the constructors private for DefaultApplication
- Make DefaultApplication immutable
- Use a builder and make the constructors private for DefaultApplicationDescription
- Make DefaultApplicationDescription immutable

Change-Id: I9499981bd2c0f48aede40682260d51eeae2cab98
diff --git a/core/api/src/main/java/org/onosproject/app/DefaultApplicationDescription.java b/core/api/src/main/java/org/onosproject/app/DefaultApplicationDescription.java
index 2e0988b..3862718 100644
--- a/core/api/src/main/java/org/onosproject/app/DefaultApplicationDescription.java
+++ b/core/api/src/main/java/org/onosproject/app/DefaultApplicationDescription.java
@@ -15,15 +15,17 @@
  */
 package org.onosproject.app;
 
-import org.onosproject.core.ApplicationRole;
-import org.onosproject.core.Version;
-import org.onosproject.security.Permission;
-
 import java.net.URI;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 
+import org.onosproject.core.ApplicationRole;
+import org.onosproject.core.Version;
+import org.onosproject.security.Permission;
+
+import com.google.common.collect.ImmutableList;
+
 import static com.google.common.base.MoreObjects.toStringHelper;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
@@ -31,7 +33,7 @@
 /**
  * Default implementation of network control/management application descriptor.
  */
-public class DefaultApplicationDescription implements ApplicationDescription {
+public final class DefaultApplicationDescription implements ApplicationDescription {
 
     private final String name;
     private final Version version;
@@ -49,6 +51,14 @@
     private final List<String> requiredApps;
 
     /**
+     * Default constructor is hidden to prevent calls to new.
+     */
+    private DefaultApplicationDescription() {
+        //  Should not happen
+        throw new UnsupportedOperationException();
+    }
+
+    /**
      * Creates a new application descriptor using the supplied data.
      *
      * @param name         application name
@@ -66,27 +76,26 @@
      * @param features     application features
      * @param requiredApps list of required application names
      */
-    public DefaultApplicationDescription(String name, Version version, String title,
-                                         String description, String origin, String category,
-                                         String url, String readme, byte[] icon,
-                                         ApplicationRole role, Set<Permission> permissions,
-                                         URI featuresRepo, List<String> features,
-                                         List<String> requiredApps) {
-        this.name = checkNotNull(name, "Name cannot be null");
-        this.version = checkNotNull(version, "Version cannot be null");
-        this.title = checkNotNull(title, "Title cannot be null");
-        this.description = checkNotNull(description, "Description cannot be null");
-        this.origin = checkNotNull(origin, "Origin cannot be null");
-        this.category = checkNotNull(category, "Category cannot be null");
+    private DefaultApplicationDescription(String name, Version version, String title,
+                                          String description, String origin, String category,
+                                          String url, String readme, byte[] icon,
+                                          ApplicationRole role, Set<Permission> permissions,
+                                          URI featuresRepo, List<String> features,
+                                          List<String> requiredApps) {
+        this.name = name;
+        this.version = version;
+        this.title = title;
+        this.description = description;
+        this.origin = origin;
+        this.category = category;
         this.url = url;
-        this.readme = checkNotNull(readme, "Readme cannot be null");
+        this.readme = readme;
         this.icon = icon;
-        this.role = checkNotNull(role, "Role cannot be null");
-        this.permissions = checkNotNull(permissions, "Permissions cannot be null");
+        this.role = role;
+        this.permissions = permissions;
         this.featuresRepo = Optional.ofNullable(featuresRepo);
-        this.features = checkNotNull(features, "Features cannot be null");
-        this.requiredApps = checkNotNull(requiredApps, "Required apps cannot be null");
-        checkArgument(!features.isEmpty(), "There must be at least one feature");
+        this.features = ImmutableList.copyOf(features);
+        this.requiredApps = ImmutableList.copyOf(requiredApps);
     }
 
     @Override
@@ -177,4 +186,220 @@
                 .add("requiredApps", requiredApps)
                 .toString();
     }
+
+    /**
+     * Returns a default application description builder.
+     *
+     * @return builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Default application description builder.
+     */
+    public static final class Builder {
+
+        private String name;
+        private Version version;
+        private String title;
+        private String description;
+        private String category;
+        private String url;
+        private String readme;
+        private byte[] icon;
+        private String origin;
+        private ApplicationRole role;
+        private Set<Permission> permissions;
+        private URI featuresRepo;
+        private List<String> features;
+        private List<String> requiredApps;
+
+        /**
+         * Default constructor for the builder.
+         */
+        public Builder() {}
+
+        /**
+         * Adds an application id.
+         *
+         * @param name application name
+         * @return builder
+         */
+        public Builder withName(String name) {
+            this.name = name;
+            return this;
+        }
+
+        /**
+         * Adds a version string.
+         *
+         * @param version version string
+         * @return builder
+         */
+        public Builder withVersion(Version version) {
+            this.version = version;
+            return this;
+        }
+
+        /**
+         * Adds a title string.
+         *
+         * @param title title string
+         * @return builder
+         */
+        public Builder withTitle(String title) {
+            this.title = title;
+            return this;
+        }
+
+        /**
+         * Adds a description string.
+         *
+         * @param description description string
+         * @return builder
+         */
+        public Builder withDescription(String description) {
+            this.description = description;
+            return this;
+        }
+
+        /**
+         * Adds a category string.
+         *
+         * @param category category string
+         * @return builder
+         */
+        public Builder withCategory(String category) {
+            this.category = category;
+            return this;
+        }
+
+        /**
+         * Adds a URL string.
+         *
+         * @param url url string
+         * @return builder
+         */
+        public Builder withUrl(String url) {
+            this.url = url;
+            return this;
+        }
+
+        /**
+         * Adds a readme string.
+         *
+         * @param readme readme string
+         * @return builder
+         */
+        public Builder withReadme(String readme) {
+            this.readme = readme;
+            return this;
+        }
+
+        /**
+         * Adds an icon.
+         *
+         * @param icon icon data
+         * @return builder
+         */
+        public Builder withIcon(byte[] icon) {
+            this.icon = icon;
+            return this;
+        }
+
+        /**
+         * Adds an origin string.
+         *
+         * @param origin origin string
+         * @return builder
+         */
+        public Builder withOrigin(String origin) {
+            this.origin = origin;
+            return this;
+        }
+
+        /**
+         * Adds an application role.
+         *
+         * @param role application role
+         * @return builder
+         */
+        public Builder withRole(ApplicationRole role) {
+            this.role = role;
+            return this;
+        }
+
+        /**
+         * Adds a permissions set.
+         *
+         * @param permissions permissions set
+         * @return builder
+         */
+        public Builder withPermissions(Set<Permission> permissions) {
+            this.permissions = permissions;
+            return this;
+        }
+
+        /**
+         * Adds a URI for a features repository.
+         *
+         * @param featuresRepo Optional URI for a features repository
+         * @return builder
+         */
+        public Builder withFeaturesRepo(URI featuresRepo) {
+            this.featuresRepo = featuresRepo;
+            return this;
+        }
+
+        /**
+         * Adds a features list.
+         *
+         * @param features features list
+         * @return builder
+         */
+        public Builder withFeatures(List<String> features) {
+            this.features = features;
+            return this;
+        }
+
+        /**
+         * Adds a list of required applications.
+         *
+         * @param requiredApps List of name strings of required applications
+         * @return builder
+         */
+        public Builder withRequiredApps(List<String> requiredApps) {
+            this.requiredApps = requiredApps;
+            return this;
+        }
+
+        /**
+         * Builds a default application object from the gathered parameters.
+         *
+         * @return new default application
+         */
+        public DefaultApplicationDescription build() {
+            checkNotNull(name, "Name cannot be null");
+            checkNotNull(version, "Version cannot be null");
+            checkNotNull(title, "Title cannot be null");
+            checkNotNull(description, "Description cannot be null");
+            checkNotNull(origin, "Origin cannot be null");
+            checkNotNull(category, "Category cannot be null");
+            checkNotNull(readme, "Readme cannot be null");
+            checkNotNull(role, "Role cannot be null");
+            checkNotNull(permissions, "Permissions cannot be null");
+            checkNotNull(features, "Features cannot be null");
+            checkNotNull(requiredApps, "Required apps cannot be null");
+            checkArgument(!features.isEmpty(), "There must be at least one feature");
+
+            return new DefaultApplicationDescription(name, version, title,
+                                          description, origin, category,
+                                          url, readme, icon,
+                                          role, permissions,
+                                          featuresRepo, features,
+                                          requiredApps);
+        }
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/core/DefaultApplication.java b/core/api/src/main/java/org/onosproject/core/DefaultApplication.java
index f780623..1eb83b4 100644
--- a/core/api/src/main/java/org/onosproject/core/DefaultApplication.java
+++ b/core/api/src/main/java/org/onosproject/core/DefaultApplication.java
@@ -17,6 +17,8 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+
+import org.onosproject.app.ApplicationDescription;
 import org.onosproject.security.Permission;
 
 import java.net.URI;
@@ -32,7 +34,7 @@
 /**
  * Default implementation of network control/management application descriptor.
  */
-public class DefaultApplication implements Application {
+public final class DefaultApplication implements Application {
 
     private final ApplicationId appId;
     private final Version version;
@@ -50,6 +52,14 @@
     private final List<String> requiredApps;
 
     /**
+     * Default constructor is hidden to prevent calls to new.
+     */
+    private DefaultApplication() {
+        // should never happen
+        throw new UnsupportedOperationException();
+    }
+
+    /**
      * Creates a new application descriptor using the supplied data.
      *
      * @param appId        application identifier
@@ -67,33 +77,26 @@
      * @param features     application features
      * @param requiredApps list of required application names
      */
-    public DefaultApplication(ApplicationId appId, Version version, String title,
+    private DefaultApplication(ApplicationId appId, Version version, String title,
                               String description, String origin, String category,
                               String url, String readme, byte[] icon,
                               ApplicationRole role, Set<Permission> permissions,
                               Optional<URI> featuresRepo, List<String> features,
                               List<String> requiredApps) {
-        this.appId = checkNotNull(appId, "ID cannot be null");
-        this.version = checkNotNull(version, "Version cannot be null");
-        this.title = checkNotNull(title, "Title cannot be null");
-        this.description = checkNotNull(description, "Description cannot be null");
-        this.origin = checkNotNull(origin, "Origin cannot be null");
-        this.category = checkNotNull(category, "Category cannot be null");
+        this.appId = appId;
+        this.version = version;
+        this.title = title;
+        this.description = description;
+        this.origin = origin;
+        this.category = category;
         this.url = url;
-        this.readme = checkNotNull(readme, "Readme cannot be null");
+        this.readme = readme;
         this.icon = icon == null ? new byte[0] : icon.clone();
-        this.role = checkNotNull(role, "Role cannot be null");
-        this.permissions = ImmutableSet.copyOf(
-                checkNotNull(permissions, "Permissions cannot be null")
-        );
-        this.featuresRepo = checkNotNull(featuresRepo, "Features repo cannot be null");
-        this.features = ImmutableList.copyOf(
-                checkNotNull(features, "Features cannot be null")
-        );
-        this.requiredApps = ImmutableList.copyOf(
-                checkNotNull(requiredApps, "Required apps cannot be null")
-        );
-        checkArgument(!features.isEmpty(), "There must be at least one feature");
+        this.role = role;
+        this.permissions = ImmutableSet.copyOf(permissions);
+        this.featuresRepo = featuresRepo;
+        this.features = ImmutableList.copyOf(features);
+        this.requiredApps = ImmutableList.copyOf(requiredApps);
     }
 
     @Override
@@ -217,4 +220,317 @@
                 .add("requiredApps", requiredApps)
                 .toString();
     }
+
+    /**
+     * Returns a default application builder.
+     *
+     * @return builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Creates a new builder as a copy of an existing builder.
+     *
+     * @param builder existing builder to copy
+     * @return new builder
+     */
+    public static Builder builder(Builder builder) {
+        return new Builder(builder);
+    }
+
+    /**
+     * Creates a new builder as a copy of an existing application.
+     *
+     * @param application existing application to copy
+     * @return new builder
+     */
+    public static Builder builder(Application application) {
+        return new Builder(application);
+    }
+
+    /**
+     * Creates a new builder as a copy of an existing application description.
+     *
+     * @param appDesc existing application description
+     * @return new builder
+     */
+    public static Builder builder(ApplicationDescription appDesc) {
+        return new Builder(appDesc);
+    }
+
+
+    /**
+     * Default application builder.
+     */
+    public static final class Builder {
+
+        private ApplicationId appId;
+        private Version version;
+        private String title;
+        private String description;
+        private String category;
+        private String url;
+        private String readme;
+        private byte[] icon;
+        private String origin;
+        private ApplicationRole role;
+        private Set<Permission> permissions;
+        private Optional<URI> featuresRepo;
+        private List<String> features;
+        private List<String> requiredApps;
+
+        /**
+         * Default constructor for the builder.
+         */
+        public Builder() {}
+
+        /**
+         * Updates the builder to be a copy of an existing builder.
+         *
+         * @param builder existing builder to copy
+         */
+        public Builder(Builder builder) {
+            this.appId = builder.appId;
+            this.version = builder.version;
+            this.title = builder.title;
+            this.description = builder.description;
+            this.category = builder.category;
+            this.url = builder.url;
+            this.readme = builder.readme;
+            this.icon = builder.icon;
+            this.origin = builder.origin;
+            this.role = builder.role;
+            this.permissions = builder.permissions;
+            this.featuresRepo = builder.featuresRepo;
+            this.features = builder.features;
+            this.requiredApps = builder.requiredApps;
+        }
+
+        /**
+         * Updates the builder to be a copy of an existing application.
+         *
+         * @param application existing application to copy
+         */
+        public Builder(Application application) {
+            this.appId = application.id();
+            this.version = application.version();
+            this.title = application.title();
+            this.description = application.description();
+            this.category = application.category();
+            this.url = application.url();
+            this.readme = application.readme();
+            this.icon = application.icon();
+            this.origin = application.origin();
+            this.role = application.role();
+            this.permissions = application.permissions();
+            this.featuresRepo = application.featuresRepo();
+            this.features = application.features();
+            this.requiredApps = application.requiredApps();
+        }
+
+        /**
+         * Updates the builder to be a copy of an existing application description.
+         *
+         * @param appDesc existing application description
+         */
+        public Builder(ApplicationDescription appDesc) {
+            this.version = appDesc.version();
+            this.title = appDesc.title();
+            this.description = appDesc.description();
+            this.category = appDesc.category();
+            this.url = appDesc.url();
+            this.readme = appDesc.readme();
+            this.icon = appDesc.icon();
+            this.origin = appDesc.origin();
+            this.role = appDesc.role();
+            this.permissions = appDesc.permissions();
+            this.featuresRepo = appDesc.featuresRepo();
+            this.features = appDesc.features();
+            this.requiredApps = appDesc.requiredApps();
+        }
+
+        /**
+         * Adds an application id.
+         *
+         * @param appId application id
+         * @return builder
+         */
+        public Builder withAppId(ApplicationId appId) {
+            this.appId = appId;
+            return this;
+        }
+
+        /**
+         * Adds a version string.
+         *
+         * @param version version string
+         * @return builder
+         */
+        public Builder withVersion(Version version) {
+            this.version = version;
+            return this;
+        }
+
+        /**
+         * Adds a title string.
+         *
+         * @param title title string
+         * @return builder
+         */
+        public Builder withTitle(String title) {
+            this.title = title;
+            return this;
+        }
+
+        /**
+         * Adds a description string.
+         *
+         * @param description description string
+         * @return builder
+         */
+        public Builder withDescription(String description) {
+            this.description = description;
+            return this;
+        }
+
+        /**
+         * Adds a category string.
+         *
+         * @param category category string
+         * @return builder
+         */
+        public Builder withCategory(String category) {
+            this.category = category;
+            return this;
+        }
+
+        /**
+         * Adds a URL string.
+         *
+         * @param url url string
+         * @return builder
+         */
+        public Builder withUrl(String url) {
+            this.url = url;
+            return this;
+        }
+
+        /**
+         * Adds a readme string.
+         *
+         * @param readme readme string
+         * @return builder
+         */
+        public Builder withReadme(String readme) {
+            this.readme = readme;
+            return this;
+        }
+
+        /**
+         * Adds an icon.
+         *
+         * @param icon icon data
+         * @return builder
+         */
+        public Builder withIcon(byte[] icon) {
+            this.icon = icon;
+            return this;
+        }
+
+        /**
+         * Adds an origin string.
+         *
+         * @param origin origin string
+         * @return builder
+         */
+        public Builder withOrigin(String origin) {
+            this.origin = origin;
+            return this;
+        }
+
+        /**
+         * Adds an application role.
+         *
+         * @param role application role
+         * @return builder
+         */
+        public Builder withRole(ApplicationRole role) {
+            this.role = role;
+            return this;
+        }
+
+        /**
+         * Adds a permissions set.
+         *
+         * @param permissions permissions set
+         * @return builder
+         */
+        public Builder withPermissions(Set<Permission> permissions) {
+            this.permissions = permissions;
+            return this;
+        }
+
+        /**
+         * Adds a URI for a features repository.
+         *
+         * @param featuresRepo Optional URI for a features repository
+         * @return builder
+         */
+        public Builder withFeaturesRepo(Optional<URI> featuresRepo) {
+            this.featuresRepo = featuresRepo;
+            return this;
+        }
+
+        /**
+         * Adds a features list.
+         *
+         * @param features features list
+         * @return builder
+         */
+        public Builder withFeatures(List<String> features) {
+            this.features = features;
+            return this;
+        }
+
+        /**
+         * Adds a list of required applications.
+         *
+         * @param requiredApps List of name strings of required applications
+         * @return builder
+         */
+        public Builder withRequiredApps(List<String> requiredApps) {
+            this.requiredApps = requiredApps;
+            return this;
+        }
+
+        /**
+         * Builds a default application object from the gathered parameters.
+         *
+         * @return new default application
+         */
+        public DefaultApplication build() {
+            checkNotNull(appId, "ID cannot be null");
+            checkNotNull(version, "Version cannot be null");
+            checkNotNull(title, "Title cannot be null");
+            checkNotNull(description, "Description cannot be null");
+            checkNotNull(origin, "Origin cannot be null");
+            checkNotNull(category, "Category cannot be null");
+            checkNotNull(readme, "Readme cannot be null");
+            checkNotNull(role, "Role cannot be null");
+            checkNotNull(permissions, "Permissions cannot be null");
+            checkNotNull(featuresRepo, "Features repo cannot be null");
+            checkNotNull(features, "Features cannot be null");
+            checkNotNull(requiredApps, "Required apps cannot be null");
+            checkArgument(!features.isEmpty(), "There must be at least one feature");
+
+            return new DefaultApplication(appId, version, title,
+                                          description, origin, category,
+                                          url, readme, icon,
+                                          role, permissions,
+                                          featuresRepo, features,
+                                          requiredApps);
+        }
+    }
 }
diff --git a/core/api/src/test/java/org/onosproject/app/ApplicationEventTest.java b/core/api/src/test/java/org/onosproject/app/ApplicationEventTest.java
index 3cdedd2..61538f0 100644
--- a/core/api/src/test/java/org/onosproject/app/ApplicationEventTest.java
+++ b/core/api/src/test/java/org/onosproject/app/ApplicationEventTest.java
@@ -32,9 +32,22 @@
 public class ApplicationEventTest extends AbstractEventTest {
 
     private Application createApp() {
-        return new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN, CATEGORY,
-                                      URL, README, ICON, ROLE, PERMS,
-                                      Optional.of(FURL), FEATURES, APPS);
+        return DefaultApplication.builder()
+                .withAppId(APP_ID)
+                .withVersion(VER)
+                .withTitle(TITLE)
+                .withDescription(DESC)
+                .withOrigin(ORIGIN)
+                .withCategory(CATEGORY)
+                .withUrl(URL)
+                .withReadme(README)
+                .withIcon(ICON)
+                .withRole(ROLE)
+                .withPermissions(PERMS)
+                .withFeaturesRepo(Optional.of(FURL))
+                .withFeatures(FEATURES)
+                .withRequiredApps(APPS)
+                .build();
     }
 
     @Test
@@ -53,4 +66,4 @@
         validateEvent(event, APP_ACTIVATED, app, before, after);
     }
 
-}
\ No newline at end of file
+}
diff --git a/core/api/src/test/java/org/onosproject/app/DefaultApplicationDescriptionTest.java b/core/api/src/test/java/org/onosproject/app/DefaultApplicationDescriptionTest.java
index ac8d971..a935c1b 100644
--- a/core/api/src/test/java/org/onosproject/app/DefaultApplicationDescriptionTest.java
+++ b/core/api/src/test/java/org/onosproject/app/DefaultApplicationDescriptionTest.java
@@ -29,6 +29,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.onlab.junit.ImmutableClassChecker.assertThatClassIsImmutable;
 
 
 /**
@@ -53,12 +54,34 @@
     public static final List<String> FEATURES = ImmutableList.of("foo", "bar");
     public static final List<String> APPS = ImmutableList.of("fifi");
 
+    /**
+     * Checks that the DefaultApplicationDescription class is immutable.
+     */
+    @Test
+    public void testImmutability() {
+        assertThatClassIsImmutable(DefaultApplicationDescription.class);
+    }
+
     @Test
     public void basics() {
         ApplicationDescription app =
-                new DefaultApplicationDescription(APP_NAME, VER, TITLE, DESC, ORIGIN,
-                                                  CATEGORY, URL, README, ICON,
-                                                  ROLE, PERMS, FURL, FEATURES, APPS);
+            DefaultApplicationDescription.builder()
+                .withName(APP_NAME)
+                .withVersion(VER)
+                .withTitle(TITLE)
+                .withDescription(DESC)
+                .withOrigin(ORIGIN)
+                .withCategory(CATEGORY)
+                .withUrl(URL)
+                .withReadme(README)
+                .withIcon(ICON)
+                .withRole(ROLE)
+                .withPermissions(PERMS)
+                .withFeaturesRepo(FURL)
+                .withFeatures(FEATURES)
+                .withRequiredApps(APPS)
+                .build();
+
         assertEquals("incorrect id", APP_NAME, app.name());
         assertEquals("incorrect version", VER, app.version());
         assertEquals("incorrect title", TITLE, app.title());
@@ -74,4 +97,4 @@
         assertEquals("incorrect apps", APPS, app.requiredApps());
         assertTrue("incorrect toString", app.toString().contains(APP_NAME));
     }
-}
\ No newline at end of file
+}
diff --git a/core/api/src/test/java/org/onosproject/core/DefaultApplicationTest.java b/core/api/src/test/java/org/onosproject/core/DefaultApplicationTest.java
index 38113bf..b523126 100644
--- a/core/api/src/test/java/org/onosproject/core/DefaultApplicationTest.java
+++ b/core/api/src/test/java/org/onosproject/core/DefaultApplicationTest.java
@@ -28,6 +28,9 @@
 import java.util.Optional;
 import java.util.Set;
 
+import static org.onlab.junit.ImmutableClassChecker.assertThatClassIsImmutable;
+import static org.onosproject.core.DefaultApplication.Builder;
+
 import static org.junit.Assert.*;
 import static org.onosproject.app.DefaultApplicationDescriptionTest.*;
 
@@ -36,13 +39,35 @@
  */
 public class DefaultApplicationTest {
 
+    /**
+     * Checks that the DefaultApplication class is immutable.
+     */
+    @Test
+    public void testImmutability() {
+        assertThatClassIsImmutable(DefaultApplication.class);
+    }
+
     public static final ApplicationId APP_ID = new DefaultApplicationId(2, APP_NAME);
+    private Builder baseBuilder = DefaultApplication.builder()
+                .withAppId(APP_ID)
+                .withVersion(VER)
+                .withTitle(TITLE)
+                .withDescription(DESC)
+                .withOrigin(ORIGIN)
+                .withCategory(CATEGORY)
+                .withUrl(URL)
+                .withReadme(README)
+                .withIcon(ICON)
+                .withRole(ROLE)
+                .withPermissions(PERMS)
+                .withFeaturesRepo(Optional.of(FURL))
+                .withFeatures(FEATURES)
+                .withRequiredApps(APPS);
 
     @Test
     public void basics() {
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                                                 CATEGORY, URL, README, ICON, ROLE,
-                                                 PERMS, Optional.of(FURL), FEATURES, APPS);
+        Application app = baseBuilder.build();
+
         assertEquals("incorrect id", APP_ID, app.id());
         assertEquals("incorrect version", VER, app.version());
         assertEquals("incorrect title", TITLE, app.title());
@@ -62,20 +87,20 @@
 
     @Test
     public void testEquality() {
-        Application a1 = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                                                CATEGORY, URL, README, ICON, ROLE,
-                                                PERMS, Optional.of(FURL), FEATURES, APPS);
-        Application a2 = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                                                CATEGORY, URL, README, ICON, ROLE,
-                                                PERMS, Optional.of(FURL), FEATURES, APPS);
-        Application a3 = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                                                CATEGORY, URL, README, ICON, ROLE,
-                                                PERMS, Optional.empty(), FEATURES, APPS);
-        Application a4 = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN + "asd",
-                                                CATEGORY, URL, README, ICON, ROLE,
-                                                PERMS, Optional.of(FURL), FEATURES, APPS);
-        new EqualsTester().addEqualityGroup(a1, a2)
-                .addEqualityGroup(a3).addEqualityGroup(a4).testEquals();
+        Application a1 = baseBuilder.build();
+        Application a2 = DefaultApplication.builder(a1)
+                .build();
+        Application a3 = DefaultApplication.builder(baseBuilder)
+                .withFeaturesRepo(Optional.empty())
+                .build();
+        Application a4 = DefaultApplication.builder(baseBuilder)
+                .withOrigin(ORIGIN + "asd")
+                .build();
+        new EqualsTester()
+                .addEqualityGroup(a1, a2)
+                .addEqualityGroup(a3)
+                .addEqualityGroup(a4)
+                .testEquals();
     }
 
 
@@ -85,9 +110,8 @@
     public void immutableIcon() {
         byte[] iconSourceData = ICON_ORIG.clone();
 
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                CATEGORY, URL, README, iconSourceData, ROLE,
-                PERMS, Optional.of(FURL), FEATURES, APPS);
+        Application app = DefaultApplication.builder(baseBuilder)
+                .withIcon(iconSourceData).build();
 
         // can we modify the icon after getting a reference to the app?
         byte[] icon = app.icon();
@@ -126,9 +150,7 @@
 //        Set<Permission> p = PERMS_ORIG;
         Set<Permission> p = PERMS_UNSAFE;
 
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                CATEGORY, URL, README, ICON, ROLE,
-                p, Optional.of(FURL), FEATURES, APPS);
+        Application app = baseBuilder.build();
 
         Set<Permission> perms = app.permissions();
         try {
@@ -168,9 +190,7 @@
 //        List<String> f = FEATURES_ORIG;
         List<String> f = FEATURES_UNSAFE;
 
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                CATEGORY, URL, README, ICON, ROLE,
-                PERMS, Optional.of(FURL), f, APPS);
+        Application app = DefaultApplication.builder(baseBuilder).withFeatures(f).build();
 
         List<String> features = app.features();
         try {
@@ -188,9 +208,7 @@
 //        List<String> ra = REQ_APPS_ORIG;
         List<String> ra = REQ_APPS_UNSAFE;
 
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                CATEGORY, URL, README, ICON, ROLE,
-                PERMS, Optional.of(FURL), FEATURES, ra);
+        Application app = DefaultApplication.builder(baseBuilder).withRequiredApps(ra).build();
 
         List<String> reqApps = app.requiredApps();
         try {
@@ -204,11 +222,9 @@
 
     @Test
     public void nullIcon() {
-        Application app = new DefaultApplication(APP_ID, VER, TITLE, DESC, ORIGIN,
-                CATEGORY, URL, README, null, ROLE,
-                PERMS, Optional.of(FURL), FEATURES, APPS);
+        Application app = DefaultApplication.builder(baseBuilder).withIcon(null).build();
         byte[] icon = app.icon();
         assertNotNull("null icon", icon);
         assertEquals("unexpected size", 0, icon.length);
     }
-}
\ No newline at end of file
+}