[minor] Add Javadocs to CEP PatternStream

flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/PatternStream.java

@@ -64,14 +64,28 @@ PatternStream<T> withComparator(final EventComparator<T> comparator) {
  return new PatternStream<>(builder.withComparator(comparator));
  }
 
+ /**
+ * Send late arriving data to the side output identified by the given {@link OutputTag}. A record
+ * is considered late after the watermark has passed its timestamp.
+ *
+ * <p>You can get the stream of late data using
+ * {@link SingleOutputStreamOperator#getSideOutput(OutputTag)} on the
+ * {@link SingleOutputStreamOperator} resulting from the pattern processing operations.
+ */
  public PatternStream<T> sideOutputLateData(OutputTag<T> lateDataOutputTag) {
  return new PatternStream<>(builder.withLateDataOutputTag(lateDataOutputTag));
  }
 
+ /**
+ * Sets the time characteristic to processing time.
+ */
  public PatternStream<T> inProcessingTime() {
  return new PatternStream<>(builder.inProcessingTime());
  }
 
+ /**
+ * Sets the time characteristic to event time.
+ */
  public PatternStream<T> inEventTime() {
  return new PatternStream<>(builder.inEventTime());
  }