Fixing issues raised in PR review.

Author: leerho

src/main/java/org/apache/datasketches/quantiles/DoublesSketchAccessor.java

@@ -45,10 +45,12 @@ abstract class DoublesSketchAccessor extends DoublesBufferAccessor {
     final boolean forceSize,
     final int level) {
     this(checkLvl(level), ds, forceSize, level);
+    //SpotBugs CT_CONSTRUCTOR_THROW is false positive.
+    //this construction scheme is compliant with SEI CERT Oracle Coding Standard for Java / OBJ11-J
   }
 
   private DoublesSketchAccessor(
-      final boolean secure,
+      final boolean secure, //required part of Finalizer Attack prevention
       final DoublesSketch ds,
       final boolean forceSize,
       final int level) {

src/main/java/org/apache/datasketches/quantiles/ItemsSketch.java

@@ -36,7 +36,6 @@
 import static org.apache.datasketches.quantiles.PreambleUtil.extractN;
 import static org.apache.datasketches.quantiles.PreambleUtil.extractPreLongs;
 import static org.apache.datasketches.quantiles.PreambleUtil.extractSerVer;
-//import static org.apache.datasketches.quantilescommon.QuantilesAPI.EMPTY_MSG;
 
 import java.lang.reflect.Array;
 import java.util.Arrays;

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

@@ -121,7 +121,7 @@ private DirectQuickSelectSketch(
   }
 
   private DirectQuickSelectSketch(
-      final boolean secure,
+      final boolean secure, //required part of Finalizer Attack prevention
       final int lgNomLongs,
       final long seed,
       final float p,

src/main/java/org/apache/datasketches/tuple/arrayofdoubles/DirectArrayOfDoublesQuickSelectSketch.java

@@ -68,7 +68,9 @@ class DirectArrayOfDoublesQuickSelectSketch extends ArrayOfDoublesQuickSelectSke
       final int numValues,
       final long seed,
       final WritableMemory dstMem) {
-    this(validate1(nomEntries, lgResizeFactor, numValues, dstMem),
+    this(checkMemory(nomEntries, lgResizeFactor, numValues, dstMem),
+    //SpotBugs CT_CONSTRUCTOR_THROW is false positive.
+    //this construction scheme is compliant with SEI CERT Oracle Coding Standard for Java / OBJ11-J
         nomEntries,
         lgResizeFactor,
         samplingProbability,
@@ -78,7 +80,7 @@ class DirectArrayOfDoublesQuickSelectSketch extends ArrayOfDoublesQuickSelectSke
   }
 
   private DirectArrayOfDoublesQuickSelectSketch(
-      final boolean secure,
+      final boolean secure, //required part of Finalizer Attack prevention
       final int nomEntries,
       final int lgResizeFactor,
       final float samplingProbability,
@@ -115,7 +117,7 @@ private DirectArrayOfDoublesQuickSelectSketch(
     setRebuildThreshold();
   }
 
-  private static final boolean validate1(
+  private static final boolean checkMemory(
       final int nomEntries,
       final int lgResizeFactor,
       final int numValues,
@@ -133,13 +135,13 @@ private static final boolean validate1(
   DirectArrayOfDoublesQuickSelectSketch(
       final WritableMemory mem,
       final long seed) {
-    this(validate2(mem), mem, seed);
+    this(checkSerVer_Endianness(mem), mem, seed);
     //SpotBugs CT_CONSTRUCTOR_THROW is false positive.
     //this construction scheme is compliant with SEI CERT Oracle Coding Standard for Java / OBJ11-J
   }
 
   private DirectArrayOfDoublesQuickSelectSketch(
-      final boolean secure,
+      final boolean secure, //required part of Finalizer Attack prevention
       final WritableMemory mem,
       final long seed) {
     super(mem.getByte(NUM_VALUES_BYTE), seed);
@@ -159,7 +161,7 @@ private DirectArrayOfDoublesQuickSelectSketch(
     setRebuildThreshold();
   }
 
-  private static final boolean validate2(final Memory mem) {
+  private static final boolean checkSerVer_Endianness(final Memory mem) {
     final byte version = mem.getByte(SERIAL_VERSION_BYTE);
     if (version != serialVersionUID) {
       throw new SketchesArgumentException("Serial version mismatch. Expected: " + serialVersionUID