public static void validateKey(final String key) throws IllegalArgumentException {
        if (null == key)
            throw Memory.Exceptions.memoryKeyCanNotBeNull();
        if (key.isEmpty())
            throw Memory.Exceptions.memoryKeyCanNotBeEmpty();
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/util/MemoryHelper.java