code: public <MarshallT> JsonProtocolMarshallerBuilder<T> marshallerOverride(MarshallLocation marshallLocation,
                                                                             MarshallingType<MarshallT> marshallingType,
                                                                             StructuredJsonMarshaller<MarshallT> marshaller) {
          if (marshallerRegistry == null) {
              this.marshallerRegistry = MarshallerRegistry.builder();
          }
          marshallerRegistry.addMarshaller(marshallLocation, marshallingType, SimpleTypeJsonMarshallers.adapt(marshaller));
          return this;
      }
docs: Registers an override for the marshaller registry.
  
  @param marshallLocation Location to override marshaller for.
  @param marshallingType  Type to override marshaller for.
  @param marshaller       Marshaller to use for the given location and type.
  @param <MarshallT>      Type of thing being marshalled.
  @return This builder for method chaining.