diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPAddress.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPAddress.java
index d9993b0..6ca39fe 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPAddress.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPAddress.java
@@ -1,5 +1,7 @@
 package org.projectfloodlight.openflow.types;
 
+import javax.annotation.Nonnull;
+
 public abstract class IPAddress<F extends IPAddress<F>> implements OFValueType<F> {
 
     public abstract IPVersion getIpVersion();
@@ -53,7 +55,17 @@
     @Override
     public abstract int hashCode();
 
-    public static IPAddress<?> of(String ip) {
+    /** parse an IPv4Address or IPv6Address from their conventional string representation.
+     *  For details on supported representations,  refer to {@link IPv4Address#of(String)}
+     *  and {@link IPv6Address#of(String)}
+     *
+     * @param ip a string representation of an IP address
+     * @return the parsed IP address
+     * @throws NullPointerException if ip is null
+     * @throws IllegalArgumentException if string is not a valid IP address
+     */
+    @Nonnull
+    public static IPAddress<?> of(@Nonnull String ip) {
         if (ip == null) {
             throw new NullPointerException("String ip must not be null");
         }
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv4Address.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv4Address.java
index 43fefac..865fb79 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv4Address.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv4Address.java
@@ -2,6 +2,8 @@
 
 import java.util.Arrays;
 
+import javax.annotation.Nonnull;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 
 import com.google.common.hash.PrimitiveSink;
@@ -112,13 +114,27 @@
         return IPv4Address.of(raw);
     }
 
+    /** construct an IPv4Address from a 32-bit integer value.
+     *
+     * @param raw the IPAdress represented as a 32-bit integer
+     * @return the constructed IPv4Address
+     */
     public static IPv4Address of(final int raw) {
         if(raw == NONE_VAL)
             return NONE;
         return new IPv4Address(raw);
     }
 
-    public static IPv4Address of(final String string) {
+    /** parse an IPv4Address from the canonical dotted-quad representation
+     * (1.2.3.4).
+     *
+     * @param string an IPv4 address in dotted-quad representation
+     * @return the parsed IPv4 address
+     * @throws NullPointerException if string is null
+     * @throws IllegalArgumentException if string is not a valid IPv4Address
+     */
+    @Nonnull
+    public static IPv4Address of(@Nonnull final String string) throws IllegalArgumentException {
         if (string == null) {
             throw new NullPointerException("String must not be null");
         }
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6Address.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6Address.java
index 1ee9e89..83fb31a 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6Address.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/IPv6Address.java
@@ -3,6 +3,8 @@
 import java.util.Arrays;
 import java.util.regex.Pattern;
 
+import javax.annotation.Nonnull;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.projectfloodlight.openflow.exceptions.OFParseError;
 
@@ -169,7 +171,22 @@
 
     private final static Pattern colonPattern = Pattern.compile(":");
 
-    public static IPv6Address of(final String string) {
+    /** parse an IPv6Address from its conventional string representation.
+     *  <p>
+     *  Expects up to 8 groups of 16-bit hex words seperated by colons
+     *  (e.g., 2001:db8:85a3:8d3:1319:8a2e:370:7348).
+     *  <p>
+     *  Supports zero compression (e.g., 2001:db8::7348).
+     *  Does <b>not</b> currently support embedding a dotted-quad IPv4 address
+     *  into the IPv6 address (e.g., 2001:db8::192.168.0.1).
+     *
+     * @param string a string representation of an IPv6 address
+     * @return the parsed IPv6 address
+     * @throws NullPointerException if string is null
+     * @throws IllegalArgumentException if string is not a valid IPv6Address
+     */
+    @Nonnull
+    public static IPv6Address of(@Nonnull final String string) throws IllegalArgumentException {
         if (string == null) {
             throw new NullPointerException("String must not be null");
         }
@@ -225,6 +242,13 @@
         return builder.getIPv6();
     }
 
+    /** construct an IPv6 adress from two 64 bit integers representing the first and
+     *  second 8-byte blocks of the address.
+     *
+     * @param raw1 - the first 8 byte block of the address
+     * @param raw2 - the second 8 byte block of the address
+     * @return the constructed IPv6Address
+     */
     public static IPv6Address of(final long raw1, final long raw2) {
         if(raw1==NONE_VAL1 && raw2 == NONE_VAL2)
             return NONE;
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/MacAddress.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/MacAddress.java
index f592ea8..d7f044e 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/MacAddress.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/MacAddress.java
@@ -2,6 +2,8 @@
 
 import java.util.Arrays;
 
+import javax.annotation.Nonnull;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.projectfloodlight.openflow.exceptions.OFParseError;
 import org.projectfloodlight.openflow.util.HexString;
@@ -55,27 +57,38 @@
         return new MacAddress(raw);
     }
 
-    public static MacAddress of(final String string) {
+    /** Parse a mac adress from the canonical string representation as
+     *  6 hex bytes separated by colons (01:02:03:04:05:06).
+     *
+     * @param macString - a mac address in canonical string representation
+     * @return the parsed MacAddress
+     * @throws IllegalArgumentException if macString is not a valid mac adddress
+     */
+    @Nonnull
+    public static MacAddress of(@Nonnull final String macString) throws IllegalArgumentException {
+        if (macString == null) {
+            throw new NullPointerException("macString must not be null");
+        }
         int index = 0;
         int shift = 40;
         final String FORMAT_ERROR = "Mac address is not well-formed. " +
                 "It must consist of 6 hex digit pairs separated by colons: ";
 
         long raw = 0;
-        if (string.length() != 6 * 2 + 5)
-            throw new IllegalArgumentException(FORMAT_ERROR + string);
+        if (macString.length() != 6 * 2 + 5)
+            throw new IllegalArgumentException(FORMAT_ERROR + macString);
 
         while (shift >= 0) {
-            int digit1 = Character.digit(string.charAt(index++), 16);
-            int digit2 = Character.digit(string.charAt(index++), 16);
+            int digit1 = Character.digit(macString.charAt(index++), 16);
+            int digit2 = Character.digit(macString.charAt(index++), 16);
             if ((digit1 < 0) || (digit2 < 0))
-                throw new IllegalArgumentException(FORMAT_ERROR + string);
+                throw new IllegalArgumentException(FORMAT_ERROR + macString);
             raw |= ((long) (digit1 << 4 | digit2)) << shift;
 
             if (shift == 0)
                 break;
-            if (string.charAt(index++) != ':')
-                throw new IllegalArgumentException(FORMAT_ERROR + string);
+            if (macString.charAt(index++) != ':')
+                throw new IllegalArgumentException(FORMAT_ERROR + macString);
             shift -= 8;
         }
         return MacAddress.of(raw);