code: public JaversBuilder registerValueGsonTypeAdapter(Class valueType, TypeAdapter nativeAdapter) {
          registerValue(valueType);
          jsonConverterBuilder().registerNativeTypeAdapter(valueType, nativeAdapter);
          return this;
      }
docs: Registers {@link ValueType} and its custom native
  <a href="http://code.google.com/p/google-gson/">Gson</a> adapter.
  <br/><br/>
  
  Useful when you already have Gson {@link TypeAdapter}s implemented.
  
  @see TypeAdapter