Update BatchOperation class to be more generic and extensible.

- addAddOperation() and addRemoveOperation() methods are removed
  from BatchOperation class, and now the class has just addOperation() method.

- Removed AddOperation and RemoveOperation classes,
  and defined IntentBatchOperation, FlowBatchOperation and MatchActionPhase classes
  as sub-classes of BatchOperation class, for Intent, IFlow and MatchAction objects
  respectively.

- These classes include definitions of add/remove operators and helper methods
  specific to Intent, IFlow and MatchAction objects.

- Removed BatchOperationTargetId class.

- Updated unit tests.

- This task is a part of ONOS-1692.

Change-Id: Iba2f737af1fef6a6555e0e0166836865ed070fa3
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/AddOperation.java b/src/main/java/net/onrc/onos/api/batchoperation/AddOperation.java
deleted file mode 100644
index f8fb8d0..0000000
--- a/src/main/java/net/onrc/onos/api/batchoperation/AddOperation.java
+++ /dev/null
@@ -1,32 +0,0 @@
-package net.onrc.onos.api.batchoperation;
-
-/**
- * An add-operation entry of a batch operation.
- */
-public class AddOperation<T extends IBatchOperationTarget>
-        implements BatchOperationEntry<T> {
-    private final T target;
-
-    /**
-     * Creates a add-operation with specified target.
-     *
-     * @param target the target object to be assigned to this add-operation
-     */
-    public AddOperation(T target) {
-        this.target = target;
-    }
-
-    @Override
-    public BatchOperator getOperator() {
-        return BatchOperator.ADD;
-    }
-
-    /**
-     * Gets the target object which assigned to this add-operation.
-     *
-     * @return the target object which assigned to this add-operation
-     */
-    public T getTarget() {
-        return target;
-    }
-}
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperation.java b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperation.java
index cb8ddd8..7ef8c45 100644
--- a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperation.java
+++ b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperation.java
@@ -1,18 +1,18 @@
 package net.onrc.onos.api.batchoperation;
 
 import java.util.Collections;
-import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 
 /**
  * A list of BatchOperationEntry.
  *
- * @param <T> IBatchOperationTarget. This should be Intent, IFlow, or
- *        MatchAction.
+ * @param <T> the enum of operators <br>
+ *        This enum must be defined in each sub-classes.
+ *
  */
-public class BatchOperation<T extends IBatchOperationTarget> {
-    private List<BatchOperationEntry<T>> ops;
+public abstract class BatchOperation<T extends BatchOperationEntry<?, ?>> {
+    private List<T> ops;
 
     /**
      * Constructor.
@@ -38,40 +38,21 @@
     }
 
     /**
-     * Returns an iterator over the operations in this object.
-     *
-     * @return an iterator over the operations in this object
-     */
-    public Iterator<BatchOperationEntry<T>> iterator() {
-        return ops.iterator();
-    }
-
-    /**
      * Returns the operations in this object.
      *
      * @return the operations in this object
      */
-    public List<BatchOperationEntry<T>> getOperations() {
+    public List<T> getOperations() {
         return Collections.unmodifiableList(ops);
     }
 
     /**
-     * Adds an add-operation.
+     * Adds an operation.
      *
-     * @param target IBatchOperationTarget object to be added
-     * @return true if succeeded, false otherwise
+     * @param entry the operation to be added
+     * @return this object if succeeded, null otherwise
      */
-    public boolean addAddOperation(T target) {
-        return ops.add(new AddOperation<T>(target));
-    }
-
-    /**
-     * Adds a remove-operation.
-     *
-     * @param id ID of the target to be removed
-     * @return true if succeeded, false otherwise
-     */
-    public boolean addRemoveOperation(BatchOperationTargetId id) {
-        return ops.add(new RemoveOperation<T>(id));
+    public BatchOperation<T> addOperation(T entry) {
+        return ops.add(entry) ? this : null;
     }
 }
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationEntry.java b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationEntry.java
index 7274d5f..23b3e39 100644
--- a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationEntry.java
+++ b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationEntry.java
@@ -1,16 +1,41 @@
 package net.onrc.onos.api.batchoperation;
 
 /**
- * An interface for batch operation entry classes.
+ * A super class for batch operation entry classes.
  * <p>
- * This is the interface to AddOperation, UpdateOperation and RemoveOperation
- * classes which are the entry maintained by BatchOperation.
+ * This is the interface to classes which are maintained by BatchOperation as
+ * its entries.
  */
-public interface BatchOperationEntry<T extends IBatchOperationTarget> {
+public class BatchOperationEntry<T extends Enum<?>, U extends IBatchOperationTarget> {
+    private final T operator;
+    private final U target;
+
     /**
-     * Gets the BatchOperator of this operation.
+     * Constructs new instance for the entry of the BatchOperation.
      *
-     * @return the BatchOperator of this operation
+     * @param operator the operator of this operation
+     * @param target the target object of this operation
      */
-    public BatchOperator getOperator();
+    public BatchOperationEntry(T operator, U target) {
+        this.operator = operator;
+        this.target = target;
+    }
+
+    /**
+     * Gets the target object of this operation.
+     *
+     * @return the target object of this operation
+     */
+    public U getTarget() {
+        return target;
+    }
+
+    /**
+     * Gets the operator of this operation.
+     *
+     * @return the operator of this operation
+     */
+    public T getOperator() {
+        return operator;
+    }
 }
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationTargetId.java b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationTargetId.java
deleted file mode 100644
index d2d0ad1..0000000
--- a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperationTargetId.java
+++ /dev/null
@@ -1,23 +0,0 @@
-package net.onrc.onos.api.batchoperation;
-
-/**
- * An abstract class to represent ID of the batch operation target.
- * <p>
- * The sub-classes must implement equals() and hashCode() methods so that
- * instance of this interface could be used as Map keys.
- */
-public abstract class BatchOperationTargetId {
-    /**
-     * Returns a string representation of the target object's ID.
-     *
-     * @return a string representation of the target object's ID
-     */
-    @Override
-    public abstract String toString();
-
-    @Override
-    public abstract int hashCode();
-
-    @Override
-    public abstract boolean equals(Object obj);
-}
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperator.java b/src/main/java/net/onrc/onos/api/batchoperation/BatchOperator.java
deleted file mode 100644
index 0b9a2ce..0000000
--- a/src/main/java/net/onrc/onos/api/batchoperation/BatchOperator.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package net.onrc.onos.api.batchoperation;
-
-/**
- * Operators used by BatchOperation classes.
- */
-public enum BatchOperator {
-    /**
-     * Adds new target object.
-     */
-    ADD,
-
-    /**
-     * Removes existing object.
-     */
-    REMOVE,
-
-    /**
-     * Unknown operator type.
-     */
-    UNKNOWN,
-}
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/IBatchOperationTarget.java b/src/main/java/net/onrc/onos/api/batchoperation/IBatchOperationTarget.java
index 3b2d3d9..d9adaed 100644
--- a/src/main/java/net/onrc/onos/api/batchoperation/IBatchOperationTarget.java
+++ b/src/main/java/net/onrc/onos/api/batchoperation/IBatchOperationTarget.java
@@ -4,10 +4,5 @@
  * An interface of the class which is assigned to BatchOperation.
  */
 public interface IBatchOperationTarget {
-    /**
-     * Gets ID of the object.
-     *
-     * @return ID of the object
-     */
-    public BatchOperationTargetId getId();
+
 }
diff --git a/src/main/java/net/onrc/onos/api/batchoperation/RemoveOperation.java b/src/main/java/net/onrc/onos/api/batchoperation/RemoveOperation.java
deleted file mode 100644
index 52eec95..0000000
--- a/src/main/java/net/onrc/onos/api/batchoperation/RemoveOperation.java
+++ /dev/null
@@ -1,32 +0,0 @@
-package net.onrc.onos.api.batchoperation;
-
-/**
- * A remove-operation entry of a batch operation.
- */
-public class RemoveOperation<T extends IBatchOperationTarget>
-        implements BatchOperationEntry<T> {
-    private final BatchOperationTargetId targetId;
-
-    /**
-     * Creates a remove-operation with specified target.
-     *
-     * @param id the target object ID to be assigned to this remove-operation
-     */
-    public RemoveOperation(BatchOperationTargetId id) {
-        this.targetId = id;
-    }
-
-    @Override
-    public BatchOperator getOperator() {
-        return BatchOperator.REMOVE;
-    }
-
-    /**
-     * Gets the target ID to be removed.
-     *
-     * @return the target ID to be removed
-     */
-    public BatchOperationTargetId getTargetId() {
-        return targetId;
-    }
-}