private static FieldSpec serialVersionUid() {
      return FieldSpec.builder(
              long.class, "serialVersionUID", Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL)
          .initializer("0")
          .build();
    }
A generator of nested serializable Proxy classes.
value/src/main/java/com/google/auto/value/extension/serializable/processor/SerializableAutoValueExtension.java