Cleanup and rearrangements in Match structure and fields.
1. Added full documentation for the Match interface
2. Added Builder into Match interface and removed the separate class
3. Added ability to declare field prerequisites in the MatchField class and then check that they are
met using a given Match object
4. Fixed some small issues in value types and added a value type for Metadata
diff --git a/java_gen/pre-written/src/main/java/org/openflow/types/IPv4WithMask.java b/java_gen/pre-written/src/main/java/org/openflow/types/IPv4WithMask.java
index c24c4fd..0a1a6d3 100644
--- a/java_gen/pre-written/src/main/java/org/openflow/types/IPv4WithMask.java
+++ b/java_gen/pre-written/src/main/java/org/openflow/types/IPv4WithMask.java
@@ -36,7 +36,7 @@
         return res.toString();
     }
     
-    public static OFValueType<?> ofPossiblyMasked(final String string) {
+    public static IPv4WithMask of(final String string) {
         int slashPos;
         String ip = string;
         int maskBits = 0;
@@ -72,7 +72,7 @@
             return IPv4WithMask.of(ipv4, maskAddress);
         } else if (maskBits == 0) {
             // No mask
-            return ipv4;
+            return IPv4WithMask.of(ipv4, IPv4.of(0xFFFFFFFF));
         } else {
             // With mask
             int mask = (-1) << (32 - maskBits);