code: public final ParallelFlux<T> log(@Nullable String category,
  			Level level,
  			SignalType... options) {
  		return log(category, level, false, options);
  	}
docs: Observe Reactive Streams signals matching the passed filter {@code options} and use
  {@link Logger} support to handle trace implementation. Default will use the passed
  {@link Level} and java.util.logging. If SLF4J is available, it will be used
  instead.
  <p>
  Options allow fine grained filtering of the traced signal, for instance to only
  capture onNext and onError:
  <pre>
  ParallelFlux.log("category", Level.INFO, SignalType.ON_NEXT,
  SignalType.ON_ERROR)
  
  <p>
  <img class="marble" src="doc-files/marbles/logForFlux.svg" alt="">
  
  @param category to be mapped into logger configuration (e.g. org.springframework
  .reactor). If category ends with "." like "reactor.", a generated operator
  suffix will complete, e.g. "reactor.Parallel.Map".
  @param level the {@link Level} to enforce for this tracing ParallelFlux (only
  FINEST, FINE, INFO, WARNING and SEVERE are taken into account)
  @param options a vararg {@link SignalType} option to filter log messages
  
  @return a new unaltered {@link ParallelFlux}