code: @Beta
      public boolean containsCustomEventMappingFor(final String eventType) {
          if (eventType == null || eventType.isEmpty()) {
              return false;
          } else {
              return this.eventTypeToEventDataMapping.containsKey(canonicalizeEventType(eventType));
          }
      }
docs: Checks if an event mapping with the given eventType exists.
  
  @param eventType the event type name.
  @return true if the mapping exists, false otherwise.