java_gen: use Arrays.copyOf() instead of .clone() for defensive copy

@gregor-bsn convinced me it's better :)
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 73b1a7d..43a7a17 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
@@ -1,5 +1,7 @@
 package org.projectfloodlight.openflow.types;
 
+import java.util.Arrays;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 
 import com.google.common.hash.PrimitiveSink;
@@ -133,7 +135,7 @@
                 }
             }
         }
-        return bytesCache.clone();
+        return Arrays.copyOf(bytesCache, bytesCache.length);
     }
 
     @Override
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 853bb65..c9dea13 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
@@ -1,9 +1,11 @@
 package org.projectfloodlight.openflow.types;
 
+import java.util.Arrays;
 import java.util.regex.Pattern;
 
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.projectfloodlight.openflow.exceptions.OFParseError;
+
 import com.google.common.hash.PrimitiveSink;
 import com.google.common.primitives.Longs;
 
@@ -228,7 +230,7 @@
                 }
             }
         }
-        return bytesCache.clone();
+        return Arrays.copyOf(bytesCache, bytesCache.length);
     }
 
     @Override
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 48a4faf..f592ea8 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
@@ -1,5 +1,7 @@
 package org.projectfloodlight.openflow.types;
 
+import java.util.Arrays;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.projectfloodlight.openflow.exceptions.OFParseError;
 import org.projectfloodlight.openflow.util.HexString;
@@ -95,7 +97,7 @@
                 }
             }
         }
-        return bytesCache.clone();
+        return Arrays.copyOf(bytesCache, bytesCache.length);
     }
 
     /**
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/OFVlanVidMatch.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/OFVlanVidMatch.java
index 51f3776..0fae3e6 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/OFVlanVidMatch.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/OFVlanVidMatch.java
@@ -1,5 +1,7 @@
 package org.projectfloodlight.openflow.types;
 
+import java.util.Arrays;
+
 import javax.annotation.Nullable;
 
 import org.jboss.netty.buffer.ChannelBuffer;
@@ -155,7 +157,7 @@
                 }
             }
         }
-        return bytesCache.clone();
+        return Arrays.copyOf(bytesCache, bytesCache.length);
     }
 
     public void write2Bytes(ChannelBuffer c) {
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/VlanVid.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/VlanVid.java
index 86633a5..2e675d4 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/VlanVid.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/VlanVid.java
@@ -1,5 +1,7 @@
 package org.projectfloodlight.openflow.types;
 
+import java.util.Arrays;
+
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.projectfloodlight.openflow.exceptions.OFParseError;
 
@@ -79,7 +81,7 @@
                 }
             }
         }
-        return bytesCache.clone();
+        return Arrays.copyOf(bytesCache, bytesCache.length);
     }
 
     public void write2Bytes(ChannelBuffer c) {