flink-instrumentation/workspace/flink-1.4.1-instrumented/flink-1.4.1/flink-runtime/src/main/java/org/apache/flink/runtime/state/heap/CopyOnWriteStateTable.java
/**
	 * Removes the mapping with the specified key/namespace composite key from this map, returning the state that was
	 * found under the entry.
	 *
	 * @param key       the key of the mapping to remove. Not null.
	 * @param namespace the namespace of the mapping to remove. Not null.
	 * @return the value of the removed mapping or {@code null} if no mapping
	 * for the specified key was found.
	 */
Removes the mapping with the specified key/namespace composite key from this map, returning the state that was
found under the entry.

@param key       the key of the mapping to remove. Not null.
@param namespace the namespace of the mapping to remove. Not null.
@return the value of the removed mapping or  null if no mapping
for the specified key was found.
Removes the mapping with the specified key / namespace composite key from this map returning the state that was found under the entry . @param key the key of the mapping to remove . Not null . @param namespace the namespace of the mapping to remove . Not null . @return the value of the removed mapping or null if no mapping for the specified key was found .
S removeAndGetOld(K key, N namespace) {
		final StateTableEntry<K, N, S> e = removeEntry(key, namespace);
		return e != null ?
				(e.stateVersion < highestRequiredSnapshotVersion ?
						getStateSerializer().copy(e.state) :
						e.state) :
				null;
	}
S removeAndGetOld ( K key , N namespace ) { final StateTableEntry < K , N , S > e = removeEntry ( key , namespace ) ; return e != null ? ( e . stateVersion < highestRequiredSnapshotVersion ? getStateSerializer ( ) . copy ( e . state ) : e . state ) : null ; }
Removes the mapping with the specified key/namespace composite key from this map, returning the state that was
 found under the entry.
Removes the mapping with the specified key / namespace composite key from this map returning the state that was found under the entry .
// copy-on-write check for state