EventProducer getProducerForEventType(Class<?> type) {
    return producersByType.get(type);
  }
Retrieves the currently registered producer for {@code type}.  If no producer is currently registered for
{@code type}, this method will return {@code null}.

@param type type of producer to retrieve.
@return currently registered producer, or {@code null}.
otto/src/main/java/com/squareup/otto/Bus.java