All except 2 of the fixes here were security related fixes to harden our

classes against "finalizer attacks".

See https://wiki.sei.cmu.edu/confluence/display/java/OBJ11-J.+Be+wary+of+letting+constructors+throw+exceptions

Author: leerho

src/main/java/org/apache/datasketches/fdt/FdtSketch.java

@@ -46,7 +46,7 @@
  *
  * @author Lee Rhodes
  */
-public class FdtSketch extends ArrayOfStringsSketch {
+public final class FdtSketch extends ArrayOfStringsSketch {
 
   /**
    * Create new instance of Frequent Distinct Tuples sketch with the given

src/main/java/org/apache/datasketches/hll/CouponHashSet.java

@@ -42,7 +42,7 @@
  * @author Lee Rhodes
  * @author Kevin Lang
  */
-class CouponHashSet extends CouponList {
+final class CouponHashSet extends CouponList {
 
   /**
    * Constructs this sketch with the intent of loading it with data

src/main/java/org/apache/datasketches/hll/CouponList.java

@@ -41,6 +41,11 @@ class CouponList extends AbstractCoupons {
   int couponCount;
   int[] couponIntArr;
 
+  @Override
+  protected final void finalize() {
+    // SpotBugs CT_CONSTUCTOR_THROW, OBJ11-J
+  }
+
   /**
    * New instance constructor for LIST or SET.
    * @param lgConfigK the configured Lg K

src/main/java/org/apache/datasketches/hll/DirectAuxHashMap.java

@@ -36,7 +36,7 @@
 /**
  * @author Lee Rhodes
  */
-class DirectAuxHashMap implements AuxHashMap {
+final class DirectAuxHashMap implements AuxHashMap {
   private final DirectHllArray host; //hosts the WritableMemory and read-only Memory
   private final boolean readOnly;
 

src/main/java/org/apache/datasketches/hll/DirectCouponHashSet.java

@@ -42,7 +42,7 @@
 /**
  * @author Lee Rhodes
  */
-class DirectCouponHashSet extends DirectCouponList {
+final class DirectCouponHashSet extends DirectCouponList {
 
   //Constructs this sketch with data.
   DirectCouponHashSet(final int lgConfigK, final TgtHllType tgtHllType,

src/main/java/org/apache/datasketches/hll/DirectCouponList.java

@@ -61,6 +61,11 @@ class DirectCouponList extends AbstractCoupons {
   Memory mem;
   final boolean compact;
 
+  @Override
+  protected final void finalize() {
+    // SpotBugs CT_CONSTUCTOR_THROW, OBJ11-J
+  }
+
   //called from newInstance, writableWrap and DirectCouponHashSet
   DirectCouponList(final int lgConfigK, final TgtHllType tgtHllType, final CurMode curMode,
       final WritableMemory wmem) {

src/main/java/org/apache/datasketches/hll/DirectHllArray.java

@@ -59,6 +59,11 @@ abstract class DirectHllArray extends AbstractHllArray {
   long memAdd;
   final boolean compact;
 
+  @Override
+  protected final void finalize() {
+    // SpotBugs CT_CONSTUCTOR_THROW, OBJ11-J
+  }
+
   //Memory must be already initialized and may have data
   DirectHllArray(final int lgConfigK, final TgtHllType tgtHllType, final WritableMemory wmem) {
     super(lgConfigK, tgtHllType, CurMode.HLL);

src/main/java/org/apache/datasketches/hll/HeapAuxHashMap.java

@@ -33,7 +33,7 @@
  * @author Lee Rhodes
  * @author Kevin Lang
  */
-class HeapAuxHashMap implements AuxHashMap {
+final class HeapAuxHashMap implements AuxHashMap {
   private final int lgConfigK; //required for #slot bits
   private int lgAuxArrInts;
   private int auxCount;

src/main/java/org/apache/datasketches/hllmap/UniqueCountMap.java

@@ -80,7 +80,7 @@
  * @author Alexander Saydakov
  * @author Kevin Lang
  */
-public class UniqueCountMap {
+public final class UniqueCountMap {
   private static final String LS = System.getProperty("line.separator");
   private static final int NUM_LEVELS = 10; // total of single coupon + traverse + coupon maps + hll
   private static final int NUM_TRAVERSE_MAPS = 3;

src/main/java/org/apache/datasketches/kll/KllItemsSketchSortedView.java

@@ -56,6 +56,11 @@ public class KllItemsSketchSortedView<T> implements GenericSortedView<T>, Partit
   private final T minItem;
   private final Class<T> clazz;
 
+  @Override
+  protected final void finalize() {
+    // SpotBugs CT_CONSTUCTOR_THROW, OBJ11-J
+  }
+
   /**
    * Construct from elements for testing only.
    * @param quantiles sorted array of quantiles