code: public MarshallerRegistry merge(MarshallerRegistry.Builder marshallerRegistryOverrides) {
          if(marshallerRegistryOverrides == null) {
              return this;
          }
          Builder merged = MarshallerRegistry.builder();
          merged.copyMarshallersFromRegistry(this.marshallers);
          merged.copyMarshallersFromRegistry(marshallerRegistryOverrides.marshallers);
          return merged.build();
      }
docs: Merge the given overrides with 'this' registry. Overrides are higher precedence than 'this' registry. Both 'this'
  registry and the override registry are immutable so a new registry object is returned. If the marshallerRegistryOverrides
  are null then this method just returns the current registry since there is nothing to merge.
  
  @param marshallerRegistryOverrides Override registry.
  @return New {@link MarshallerRegistry} with marshallers merged.