[sonar] add impl

core/mogo-core-utils/src/main/java/com/mogo/eagle/core/utilcode/mogo/glide/utils/DiskLruCacheManager.java

@@ -22,7 +22,8 @@ import java.security.MessageDigest;
 public class DiskLruCacheManager {
 
 	private DiskLruCache diskLruCache;
-	private static DiskLruCacheManager instance;
+	private static volatile DiskLruCacheManager instance;
+	private static final byte[] obj = new byte[0];
 
 	private final int MAX_CACHE_SIZE = 64 * 1024 * 1024;
 
@@ -37,7 +38,7 @@ public class DiskLruCacheManager {
 
 	public static DiskLruCacheManager getInstance(Context context) {
 		if (instance == null) {
-			synchronized (DiskLruCacheManager.class) {
+			synchronized (obj) {
 				if (instance == null) {
 					instance = new DiskLruCacheManager(context.getApplicationContext());
 				}