code: public void registerDefinedSchema(DataSchema schema)
    {
      final ClassTemplateSpec spec = createFromDataSchema(schema);
      _schemaToClassMap.put(schema, spec);
      _classNameToSchemaMap.put(spec.getFullName(), schema);
    }
docs: Instead of generate spec for the specify {@link com.linkedin.data.schema.DataSchema}, assume it is already defined in the system.