java_gen: beautify toString output of OFMatch
diff --git a/java_gen/templates/custom/OFMatchV1Ver10.java b/java_gen/templates/custom/OFMatchV1Ver10.java
index 93c2ad0..8a24b2f 100644
--- a/java_gen/templates/custom/OFMatchV1Ver10.java
+++ b/java_gen/templates/custom/OFMatchV1Ver10.java
@@ -331,7 +331,7 @@
                 int dstCidrLen = getIpv4DstCidrMaskLen();
                 return dstCidrLen > 0 && dstCidrLen < 32;
             default:
-                throw new UnsupportedOperationException("OFMatch does not support masked matching on field " + field.getName());
+                return false;
         }
     }