@Override
  public final List<MethodMetadata> parseAndValidateMetadata(Class<?> targetType) {
    // any implementations must register processors
    return super.parseAndValidateMetadata(targetType);
  }
{@link Contract} base implementation that works by declaring witch annotations should be
processed and how each annotation modifies {@link MethodMetadata}
core/src/main/java/feign/DeclarativeContract.java