HADOOP-14688. Intern strings in KeyVersion and EncryptedKeyVersion. Contributed by Xiao Chen.

(cherry picked from commit ad32759fd9f33e7bd18758ad1a5a464dab3bcbd9)
(cherry picked from commit c16ecf0fe8c112437c463c8aabe3a4c0bce6d1da)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/KeyProvider.java

@@ -69,8 +69,8 @@ public abstract class KeyProvider {
 
     protected KeyVersion(String name, String versionName,
                          byte[] material) {
-      this.name = name;
-      this.versionName = versionName;
+      this.name = name == null ? null : name.intern();
+      this.versionName = versionName == null ? null : versionName.intern();
       this.material = material;
     }
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/KeyProviderCryptoExtension.java

@@ -79,8 +79,9 @@ public class KeyProviderCryptoExtension extends
     protected EncryptedKeyVersion(String keyName,
         String encryptionKeyVersionName, byte[] encryptedKeyIv,
         KeyVersion encryptedKeyVersion) {
-      this.encryptionKeyName = keyName;
-      this.encryptionKeyVersionName = encryptionKeyVersionName;
+      this.encryptionKeyName = keyName == null ? null : keyName.intern();
+      this.encryptionKeyVersionName = encryptionKeyVersionName == null ?
+          null : encryptionKeyVersionName.intern();
       this.encryptedKeyIv = encryptedKeyIv;
       this.encryptedKeyVersion = encryptedKeyVersion;
     }