[hotfix] [cep] Fix incorrect CompatibilityResult.requiresMigration ca…

…lls in CEP

flink-core/src/main/java/org/apache/flink/api/common/typeutils/CompatibilityResult.java

@@ -21,6 +21,8 @@
 import org.apache.flink.annotation.PublicEvolving;
 import org.apache.flink.util.Preconditions;
 
+import javax.annotation.Nonnull;
+
 /**
  * A {@code CompatibilityResult} contains information about whether or not data migration
  * is required in order to continue using new serializers for previously serialized data.
@@ -60,10 +62,10 @@ public static <T> CompatibilityResult<T> compatible() {
 	 *
 	 * @return a result that signals migration is necessary, also providing a convert deserializer.
 	 */
-	public static <T> CompatibilityResult<T> requiresMigration(TypeDeserializer<T> convertDeserializer) {
+	public static <T> CompatibilityResult<T> requiresMigration(@Nonnull TypeDeserializer<T> convertDeserializer) {
 		Preconditions.checkNotNull(convertDeserializer, "Convert deserializer cannot be null.");
 
-		return new CompatibilityResult<>(true, Preconditions.checkNotNull(convertDeserializer));
+		return new CompatibilityResult<>(true, convertDeserializer);
 	}
 
 	/**

flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/NFA.java

@@ -1108,7 +1108,7 @@ public CompatibilityResult<NFA<T>> ensureCompatibility(TypeSerializerConfigSnaps
 				}
 			}
 
-			return CompatibilityResult.requiresMigration(null);
+			return CompatibilityResult.requiresMigration();
 		}
 
 		private void serializeStates(Set<State<T>> states, DataOutputView out) throws IOException {

flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/SharedBuffer.java

@@ -1163,7 +1163,7 @@ public CompatibilityResult<SharedBuffer<K, V>> ensureCompatibility(TypeSerialize
 				}
 			}
 
-			return CompatibilityResult.requiresMigration(null);
+			return CompatibilityResult.requiresMigration();
 		}
 	}