Mostly spelling errors and documentation corrections.

src/main/java/org/apache/datasketches/theta/ConcurrentHeapThetaBuffer.java

@@ -94,7 +94,7 @@ private static int computeLogBufferSize(final int lgNomLongs, final long exactSi
    * @param hash to be propagated
    */
   private boolean propagateToSharedSketch(final long hash) {
-    //noinspection StatementWithEmptyBody
+    //no inspection StatementWithEmptyBody
     while (localPropagationInProgress.get()) {
     } //busy wait until previous propagation completed
     localPropagationInProgress.set(true);
@@ -108,7 +108,7 @@ private boolean propagateToSharedSketch(final long hash) {
    * Propagates the content of the buffer as a sketch to the shared sketch
    */
   private void propagateToSharedSketch() {
-    //noinspection StatementWithEmptyBody
+    //no inspection StatementWithEmptyBody
     while (localPropagationInProgress.get()) {
     } //busy wait until previous propagation completed
 

src/main/java/org/apache/datasketches/theta/ConcurrentSharedThetaSketch.java

@@ -63,8 +63,8 @@ static long computeExactLimit(long k, double error) {
   void endPropagation(AtomicBoolean localPropagationInProgress, boolean isEager);
 
   /**
-   * Returns the value of the volatile theta manged by the shared sketch
-   * @return the value of the volatile theta manged by the shared sketch
+   * Returns the value of the volatile theta managed by the shared sketch
+   * @return the value of the volatile theta managed by the shared sketch
    */
   long getVolatileTheta();
 
@@ -124,7 +124,7 @@ boolean propagate(final AtomicBoolean localPropagationInProgress, final Sketch s
   //
   //For the external user all of the below methods can be obtained by casting the shared
   //sketch to UpdateSketch.  However, these methods here also act as an alias so that an
-  //attempt to access these methods from the local buffer will be divered to the shared
+  //attempt to access these methods from the local buffer will be diverted to the shared
   //sketch.
 
   //From Sketch

src/main/java/org/apache/datasketches/theta/DirectQuickSelectSketch.java

@@ -323,6 +323,10 @@ UpdateReturnState hashUpdate(final long hash) {
 
           memReqSvr_ = (memReqSvr_ == null) ? wmem_.getMemoryRequestServer() : memReqSvr_;
 
+          if (memReqSvr_ == null) { //in case the MRS is not enabled or null.
+            throw new SketchesArgumentException("Out of Memory, MemoryRequestServer is null, cannot expand.");
+          }
+
           final WritableMemory newDstMem = memReqSvr_.request(wmem_,reqBytes);
 
           moveAndResize(wmem_, preambleLongs, lgArrLongs, newDstMem, tgtLgArrLongs, thetaLong);

src/main/java/org/apache/datasketches/theta/Rebuilder.java

@@ -84,7 +84,7 @@ static final void quickSelectAndRebuild(final WritableMemory mem, final int prea
   }
 
   /**
-   * Moves me (the entire sketch) to a new larger Memory location and rebuilds the hash table.
+   * Moves me (the entire updatable sketch) to a new larger Memory location and rebuilds the hash table.
    * This assumes a Memory preamble of standard form with the correct value of thetaLong.
    * Afterwards, the caller must update the local Memory reference, lgArrLongs
    * and hashTableThreshold from the dstMemory and free the source Memory.

src/main/java/org/apache/datasketches/theta/SetOperation.java

@@ -245,7 +245,7 @@ public static int getMaxAnotBResultBytes(final int nomEntries) {
    * <p>Note: Only certain set operators during stateful operations can be serialized.
    * Only when they are stored into Memory will this be relevant.</p>
    *
-   * @param that A different non-null object
+   * @param that A different non-null and alive object
    * @return true if the backing resource of <i>this</i> is the same as the backing resource
    * of <i>that</i>.
    */

src/main/java/org/apache/datasketches/theta/SetOperationBuilder.java

@@ -66,7 +66,7 @@ public SetOperationBuilder() {
    * Sets the Maximum Nominal Entries (max K) for this set operation. The effective value of K of the result of a
    * Set Operation can be less than max K, but never greater.
    * The minimum value is 16 and the maximum value is 67,108,864, which is 2^26.
-   * @param nomEntries <a href="{@docRoot}/resources/dictionary.html#nomEntries">Nominal Entres</a>
+   * @param nomEntries <a href="{@docRoot}/resources/dictionary.html#nomEntries">Nominal Entries</a>
    * This will become the ceiling power of 2 if it is not a power of 2.
    * @return this SetOperationBuilder
    */

src/main/java/org/apache/datasketches/theta/Sketch.java

@@ -602,8 +602,8 @@ public static String toString(final Memory mem) {
   abstract int getCurrentPreambleLongs();
 
   /**
-   * Returns the Memory object if it exists, otherwise null.
-   * @return the Memory object if it exists, otherwise null.
+   * Returns the backing Memory object if it exists, otherwise null.
+   * @return the backing Memory object if it exists, otherwise null.
    */
   abstract Memory getMemory();