function createKeyString(keyValues) {
        return keyValues.join(ENTITY_KEY_DELIMITER);
    }
Used to compare EntityKeys are determine if they refer to the same Entity. 
    There is also an instance version of 'equals' with the same functionality. 
    @example
        // assume em1 is an EntityManager containing a number of existing entities.
        var empType = em1.metadataStore.getEntityType("Employee");
        var empKey1 = new EntityKey(empType, 1);
        // assume employee1 is an existing Employee entity
        var empKey2 = employee1.entityAspect.getKey();
        if (EntityKey.equals(empKey1, empKey2)) {
            // do something  ...
        }
    @method equals
    @static
    @param k1 {EntityKey}
    @param k2 {EntityKey}