java_gen: renamed OFChecksum128 to U128 + implement HashValue

This has the same semantics as our other Uxx types.
diff --git a/test_data/of13/bsn_gentable_bucket_stats_reply.data b/test_data/of13/bsn_gentable_bucket_stats_reply.data
index 8e0772f..84a36a6 100644
--- a/test_data/of13/bsn_gentable_bucket_stats_reply.data
+++ b/test_data/of13/bsn_gentable_bucket_stats_reply.data
@@ -22,8 +22,8 @@
 builder.setXid(0x12345678)
     .setEntries(
         ImmutableList.<OFBsnGentableBucketStatsEntry>of(
-            factory.bsnGentableBucketStatsEntry(OFChecksum128.of(0x8877665544332211L, 0xFFEEDDCCBBAA9988L)),
-            factory.bsnGentableBucketStatsEntry(OFChecksum128.of(0x1234234534564567L, 0x56786789789A89ABL))
+            factory.bsnGentableBucketStatsEntry(U128.of(0x8877665544332211L, 0xFFEEDDCCBBAA9988L)),
+            factory.bsnGentableBucketStatsEntry(U128.of(0x1234234534564567L, 0x56786789789A89ABL))
         )
     )
 -- c
diff --git a/test_data/of13/bsn_gentable_clear_request.data b/test_data/of13/bsn_gentable_clear_request.data
index 847af3c..853d463 100644
--- a/test_data/of13/bsn_gentable_clear_request.data
+++ b/test_data/of13/bsn_gentable_clear_request.data
@@ -16,8 +16,8 @@
     checksum_mask=0xFFFFFFFFFFFFFFFFFFFFFFFFFFFF0000)
 -- java
 builder.setXid(0x12345678)
-    .setChecksum(OFChecksum128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA990000L))
-    .setChecksumMask(OFChecksum128.of(0xFFFFFFFFFFFFFFFFL, 0xFFFFFFFFFFFF0000L))
+    .setChecksum(U128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA990000L))
+    .setChecksumMask(U128.of(0xFFFFFFFFFFFFFFFFL, 0xFFFFFFFFFFFF0000L))
     .setTableId(GenTableId.of(20))
 -- c
 obj = of_bsn_gentable_clear_request_new(OF_VERSION_1_3);
diff --git a/test_data/of13/bsn_gentable_entry_add.data b/test_data/of13/bsn_gentable_entry_add.data
index 02c2bb4..f813dcd 100644
--- a/test_data/of13/bsn_gentable_entry_add.data
+++ b/test_data/of13/bsn_gentable_entry_add.data
@@ -38,7 +38,7 @@
     ])
 -- java
 builder.setXid(0x12345678)
-    .setChecksum(OFChecksum128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998877L))
+    .setChecksum(U128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998877L))
     .setTableId(GenTableId.of(20))
     .setKey(
         ImmutableList.<OFBsnTlv>of(
diff --git a/test_data/of13/bsn_gentable_entry_desc_stats_reply.data b/test_data/of13/bsn_gentable_entry_desc_stats_reply.data
index 4035f4c..21291ed 100644
--- a/test_data/of13/bsn_gentable_entry_desc_stats_reply.data
+++ b/test_data/of13/bsn_gentable_entry_desc_stats_reply.data
@@ -55,7 +55,7 @@
     .setEntries(
         ImmutableList.<OFBsnGentableEntryDescStatsEntry>of(
             factory.buildBsnGentableEntryDescStatsEntry()
-                .setChecksum(OFChecksum128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998800L))
+                .setChecksum(U128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998800L))
                 .setKey(ImmutableList.<OFBsnTlv>of(
                     factory.bsnTlvs().port(OFPort.of(5))
                 ))
@@ -64,7 +64,7 @@
                 ))
                 .build(),
             factory.buildBsnGentableEntryDescStatsEntry()
-                .setChecksum(OFChecksum128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998801L))
+                .setChecksum(U128.of(0xFEDCBA9876543210L, 0xFFEECCBBAA998801L))
                 .setKey(ImmutableList.<OFBsnTlv>of(
                     factory.bsnTlvs().port(OFPort.of(6))
                 ))