code: @Experimental
      @Beta
      public static <T> FlowableTransformer<String, String> splitSimple(final String delimiter) {
          return new FlowableTransformer<String, String>() {
  
              @Override
              public Publisher<String> apply(Flowable<String> source) {
                  return new FlowableStringSplitSimple(source, delimiter);
              }
          };
      }
docs: Splits on a string delimiter, not a pattern. Is slower than RxJavaString
  1.1.1 implementation on benchmarks below but requests minimally from
  upstream and is potentially much faster when the stream is significantly truncated
  (for example by downstream {@code .take(), .takeUntil(), elementAt()}.
  
  <pre>
  Benchmark                                  Mode  Cnt       Score       Error  Units
  Benchmarks.splitRxJavaString              thrpt   10     983.128 ±    23.833  ops/s
  Benchmarks.splitRxJavaStringTake5         thrpt   10    1033.090 ±    33.083  ops/s
  Benchmarks.splitSimple                    thrpt   10     113.727 ±     2.122  ops/s
  Benchmarks.splitSimpleTake5               thrpt   10  867527.265 ± 27168.498  ops/s
  Benchmarks.splitStandard                  thrpt   10     108.880 ±     4.428  ops/s
  Benchmarks.splitStandardTake5             thrpt   10    1217.798 ±    44.237  ops/s
  Benchmarks.splitStandardWithPattern       thrpt   10     102.882 ±     5.083  ops/s
  Benchmarks.splitStandardWithPatternTake5  thrpt   10    1054.024 ±    27.906  ops/s
  </pre>
  
  @param delimiter
  string delimiter
  @param <T>
  type being streamed
  @return stream split by delimiter