code: private boolean conformsToSignature(Method m) {
          Pact pact = m.getAnnotation(Pact.class);
          boolean conforms =
              pact != null
              && MessagePact.class.isAssignableFrom(m.getReturnType())
              && m.getParameterTypes().length == 1
              && m.getParameterTypes()[0].isAssignableFrom(MessagePactBuilder.class);
  
          if (!conforms && pact != null) {
              throw new UnsupportedOperationException("Method " + m.getName() +
                  " does not conform required method signature 'public MessagePact xxx(MessagePactBuilder builder)'");
          }
          return conforms;
      }
docs: validates method signature as described at {@link Pact}