Fixing typos in the javadocs.

flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/InputGate.java

@@ -61,7 +61,9 @@ import java.io.IOException;
  *
  * <p> In the above example, two map subtasks produce the intermediate result in parallel, resulting
  * in two partitions (Partition 1 and 2). Each of these partitions is further partitioned into two
- * subpartitions -- one for each parallel reduce subtask.
+ * subpartitions -- one for each parallel reduce subtask. As shown in the Figure, each reduce task
+ * will have an input gate attached to it. This will provide its input, which will consist of one
+ * subpartition from each partition of the intermediate result.
  */
 public interface InputGate {
 

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/CheckpointBarrierHandler.java

@@ -35,12 +35,12 @@ public interface CheckpointBarrierHandler {
 
 	/**
 	 * Returns the next {@link BufferOrEvent} that the operator may consume.
-	 * This call blocks until the next BufferOrEvent is available, ir until the stream
+	 * This call blocks until the next BufferOrEvent is available, or until the stream
 	 * has been determined to be finished.
 	 * 
 	 * @return The next BufferOrEvent, or {@code null}, if the stream is finished.
-	 * @throws java.io.IOException Thrown, if the network or local disk I/O fails.
-	 * @throws java.lang.InterruptedException Thrown, if the thread is interrupted while blocking during
+	 * @throws java.io.IOException Thrown if the network or local disk I/O fails.
+	 * @throws java.lang.InterruptedException Thrown if the thread is interrupted while blocking during
 	 *                                        waiting for the next BufferOrEvent to become available.
 	 */
 	BufferOrEvent getNextNonBlocked() throws IOException, InterruptedException;
@@ -55,13 +55,13 @@ public interface CheckpointBarrierHandler {
 	/**
 	 * Cleans up all internally held resources.
 	 * 
-	 * @throws IOException Thrown, if the cleanup of I/O resources failed.
+	 * @throws IOException Thrown if the cleanup of I/O resources failed.
 	 */
 	void cleanup() throws IOException;
 
 	/**
 	 * Checks if the barrier handler has buffered any data internally.
-	 * @return True, if no data is buffered internally, false otherwise.
+	 * @return {@code True}, if no data is buffered internally, {@code false} otherwise.
 	 */
 	boolean isEmpty();
 }

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/io/StreamInputProcessor.java

@@ -76,8 +76,6 @@ public class StreamInputProcessor<IN> {
 
 	private boolean isFinished;
 
-
-
 	private final long[] watermarks;
 	private long lastEmittedWatermark;
 
@@ -101,7 +99,7 @@ public class StreamInputProcessor<IN> {
 			this.barrierHandler = new BarrierTracker(inputGate);
 		}
 		else {
-			throw new IllegalArgumentException("Unrecognized CheckpointingMode: " + checkpointMode);
+			throw new IllegalArgumentException("Unrecognized Checkpointing Mode: " + checkpointMode);
 		}
 		
 		if (checkpointListener != null) {

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/windowing/MergingWindowSet.java

@@ -41,8 +41,8 @@ import java.util.Map;
  * {@link #getStateWindow(Window)}.
  *
  * <p>A new window can be added to the set of in-flight windows using
- * {@link #addWindow(Window, MergeFunction)}, this might merge other windows and the caller
- * must react accordingly in {@link MergeFunction#merge(Object, Collection, Object, Collection)
+ * {@link #addWindow(Window, MergeFunction)}. This might merge other windows and the caller
+ * must react accordingly in the {@link MergeFunction#merge(Object, Collection, Object, Collection)
  * and adjust the outside view of windows and state.
  *
  * <p>Windows can be removed from the set of windows using {@link #retireWindow(Window)}.
@@ -70,7 +70,6 @@ public class MergingWindowSet<W extends Window> {
 	 */
 	public MergingWindowSet(MergingWindowAssigner<?, W> windowAssigner) {
 		this.windowAssigner = windowAssigner;
-
 		windows = new HashMap<>();
 	}
 
@@ -127,12 +126,12 @@ public class MergingWindowSet<W extends Window> {
 	 * {@link MergeFunction} is called.
 	 *
 	 * <p>This returns the window that is the representative of the added window after adding.
-	 * This can either be the new window itself, if no merge occured, or the newly merged
+	 * This can either be the new window itself, if no merge occurred, or the newly merged
 	 * window. Adding an element to a window or calling trigger functions should only
 	 * happen on the returned representative. This way, we never have to deal with a new window
 	 * that is immediately swallowed up by another window.
 	 *
-	 * <p>If the new window is merged the {@code MergeFunction} callback arguments also don't
+	 * <p>If the new window is merged, the {@code MergeFunction} callback arguments also don't
 	 * contain the new window as part of the list of merged windows.
 	 *
 	 * @param newWindow The new {@code Window} to add.

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/streamrecord/MultiplexingStreamRecordSerializer.java

@@ -30,8 +30,8 @@ import static java.util.Objects.requireNonNull;
 
 /**
  * Serializer for {@link StreamRecord} and {@link Watermark}. This does not behave like a normal
- * {@link TypeSerializer}, instead, this is only used at the stream task/opertator level for
- * transmitting StreamRecords} and Watermarks.
+ * {@link TypeSerializer}, instead, this is only used at the stream task/operator level for
+ * transmitting StreamRecords and Watermarks.
  *
  * @param <T> The type of value in the StreamRecord
  */