improve: GenericRetry does not provide mutable singleton instance

This might easily result in unintended side effect if someone
uses `DEFAULT` instance in one controller, changes some paramter; then uses the instance
for an other controller, in that case the changed parameter will apply also for other controller
what is quite unintuitive

Signed-off-by: Attila Mészáros <a_meszaros@apple.com>

Author: csviri

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ControllerConfiguration.java

@@ -57,7 +57,7 @@ default boolean isGenerationAware() {
   String getAssociatedReconcilerClassName();
 
   default Retry getRetry() {
-    return GenericRetry.DEFAULT;
+    return GenericRetry.defaultLimitedExponentialRetry();
   }
 
   @SuppressWarnings("rawtypes")

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/retry/GenericRetry.java

@@ -10,10 +10,15 @@ public class GenericRetry implements Retry, AnnotationConfigurable<GradualRetry>
   private double intervalMultiplier = GradualRetry.DEFAULT_MULTIPLIER;
   private long maxInterval = GradualRetry.DEFAULT_MAX_INTERVAL;
 
+  /**
+   * @deprecated use {@link GenericRetry#defaultLimitedExponentialRetry()} instead this instance.
+   *     Since GenericRetry is mutable, singleton is problematic.
+   */
+  @Deprecated(forRemoval = true)
   public static final Retry DEFAULT = new GenericRetry();
 
   public static GenericRetry defaultLimitedExponentialRetry() {
-    return (GenericRetry) DEFAULT;
+    return new GenericRetry();
   }
 
   public static GenericRetry noRetry() {