isExtensionNumber  459 third_party/protobuf/java/src/main/java/com/google/protobuf/AbstractMessage.java       if (type.isExtensionNumber(fieldNumber)) {
isExtensionNumber  973 third_party/protobuf/java/src/main/java/com/google/protobuf/Descriptors.java         if (!getContainingType().isExtensionNumber(getNumber())) {