code: @Beta
      public boolean removeCustomEventMapping(final String eventType) {
          if (!containsCustomEventMappingFor(eventType)) {
              return false;
          } else {
              this.eventTypeToEventDataMapping.remove(canonicalizeEventType(eventType));
              return true;
          }
      }
docs: Removes the mapping with the given eventType.
  
  @param eventType the event type name.
  @return true if the mapping exists and removed, false if mapping does not exists.