Clean-up numbers core TestUtilities.

Removed all public methods that are not used.
diff --git a/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/TestUtils.java b/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/TestUtils.java
index bfdb434..742de25 100644
--- a/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/TestUtils.java
+++ b/commons-numbers-core/src/test/java/org/apache/commons/numbers/core/TestUtils.java
@@ -23,11 +23,8 @@
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 
-import org.junit.jupiter.api.Assertions;
-
 /**
  * Test utilities.
- * TODO: Cleanup (remove unused and obsolete methods).
  */
 public final class TestUtils {
     /**
@@ -47,148 +44,20 @@
     public static Object serializeAndRecover(Object o) {
         try {
             // serialize the Object
-            ByteArrayOutputStream bos = new ByteArrayOutputStream();
-            ObjectOutputStream so = new ObjectOutputStream(bos);
+            final ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            final ObjectOutputStream so = new ObjectOutputStream(bos);
             so.writeObject(o);
 
             // deserialize the Object
-            ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
-            ObjectInputStream si = new ObjectInputStream(bis);
+            final ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
+            final ObjectInputStream si = new ObjectInputStream(bis);
             return si.readObject();
-        } catch (IOException ioe) {
+        } catch (final IOException ioe) {
             return null;
-        } catch (ClassNotFoundException cnfe) {
+        } catch (final ClassNotFoundException cnfe) {
             return null;
         }
     }
-
-    /**
-     * Verifies that serialization preserves equals and hashCode.
-     * Serializes the object, then recovers it and checks equals and hash code.
-     *
-     * @param object  the object to serialize and recover
-     */
-    public static void checkSerializedEquality(Object object) {
-        Object object2 = serializeAndRecover(object);
-        Assertions.assertEquals(object, object2, "Equals check");
-        Assertions.assertEquals(object.hashCode(), object2.hashCode(), "HashCode check");
-    }
-
-    /**
-     * Verifies that the relative error in actual vs. expected is less than or
-     * equal to relativeError.  If expected is infinite or NaN, actual must be
-     * the same (NaN or infinity of the same sign).
-     *
-     * @param expected expected value
-     * @param actual  observed value
-     * @param relativeError  maximum allowable relative error
-     */
-    public static void assertRelativelyEquals(double expected, double actual,
-            double relativeError) {
-        assertRelativelyEquals(null, expected, actual, relativeError);
-    }
-
-    /**
-     * Verifies that the relative error in actual vs. expected is less than or
-     * equal to relativeError.  If expected is infinite or NaN, actual must be
-     * the same (NaN or infinity of the same sign).
-     *
-     * @param msg  message to return with failure
-     * @param expected expected value
-     * @param actual  observed value
-     * @param relativeError  maximum allowable relative error
-     */
-    public static void assertRelativelyEquals(String msg, double expected,
-            double actual, double relativeError) {
-        if (Double.isNaN(expected)) {
-            Assertions.assertTrue(Double.isNaN(actual), msg);
-        } else if (Double.isNaN(actual)) {
-            Assertions.assertTrue(Double.isNaN(expected), msg);
-        } else if (Double.isInfinite(actual) || Double.isInfinite(expected)) {
-            Assertions.assertEquals(expected, actual, relativeError);
-        } else if (expected == 0.0) {
-            Assertions.assertEquals(expected, actual, relativeError, msg);
-        } else {
-            double absError = Math.abs(expected) * relativeError;
-            Assertions.assertEquals(expected, actual, absError, msg);
-        }
-    }
-
-    /**
-     * Fails iff values does not contain a number within epsilon of x.
-     *
-     * @param msg  message to return with failure
-     * @param values double array to search
-     * @param x value sought
-     * @param epsilon  tolerance
-     */
-    public static void assertContains(String msg, double[] values,
-            double x, double epsilon) {
-        for (double value : values) {
-            if (Precision.equals(value, x, epsilon)) {
-                return;
-            }
-        }
-        Assertions.fail(msg + " Unable to find " + x);
-    }
-
-    /**
-     * Fails iff values does not contain a number within epsilon of x.
-     *
-     * @param values double array to search
-     * @param x value sought
-     * @param epsilon  tolerance
-     */
-    public static void assertContains(double[] values, double x,
-            double epsilon) {
-        assertContains(null, values, x, epsilon);
-    }
-
-    /**
-     * Updates observed counts of values in quartiles.
-     * counts[0] <-> 1st quartile ... counts[3] <-> top quartile
-     */
-    public static void updateCounts(double value, long[] counts, double[] quartiles) {
-        if (value < quartiles[0]) {
-            counts[0]++;
-        } else if (value > quartiles[2]) {
-            counts[3]++;
-        } else if (value > quartiles[1]) {
-            counts[2]++;
-        } else {
-            counts[1]++;
-        }
-    }
-
-    /**
-     * Eliminates points with zero mass from densityPoints and densityValues parallel
-     * arrays.  Returns the number of positive mass points and collapses the arrays so
-     * that the first <returned value> elements of the input arrays represent the positive
-     * mass points.
-     */
-    public static int eliminateZeroMassPoints(int[] densityPoints, double[] densityValues) {
-        int positiveMassCount = 0;
-        for (int i = 0; i < densityValues.length; i++) {
-            if (densityValues[i] > 0) {
-                positiveMassCount++;
-            }
-        }
-        if (positiveMassCount < densityValues.length) {
-            int[] newPoints = new int[positiveMassCount];
-            double[] newValues = new double[positiveMassCount];
-            int j = 0;
-            for (int i = 0; i < densityValues.length; i++) {
-                if (densityValues[i] > 0) {
-                    newPoints[j] = densityPoints[i];
-                    newValues[j] = densityValues[i];
-                    j++;
-                }
-            }
-            System.arraycopy(newPoints, 0, densityPoints, 0, positiveMassCount);
-            System.arraycopy(newValues, 0, densityValues, 0, positiveMassCount);
-        }
-        return positiveMassCount;
-    }
 }