### Question:
QualifiedPathKey implements Comparable<Object> { @Override public int hashCode() { return new HashCodeBuilder() .append(this.cluster) .append(this.path) .append(this.namespace) .toHashCode(); } QualifiedPathKey(String cluster, String path);  QualifiedPathKey(String cluster, String path, String namespace); String getCluster(); String getPath(); String getNamespace(); @Override String toString(); @Override int compareTo(Object other); @Override int hashCode(); @Override boolean equals(Object other); boolean hasFederatedNS();  }### Answer:
@Test public void testNullHashCode() throws Exception { QualifiedPathKey key1 = new QualifiedPathKey(null, null); QualifiedPathKey key2 = new QualifiedPathKey(" ", " "); assertEquals(key1.hashCode(), key2.hashCode()); }