ZF-8767: Zend_Validate_NotEmpty reports self::INVALID for every type of validation error
self::INVALID is set to "Invalid type given, value should be float, string, array, boolean or integer", but it is reported for "" string, 0 integer, 0.0 float, array().
"" is an empty string, but it is a string. 0 is an integer etc. so the message is plainly wrong. It should be self::IS_EMPTY => "Value is required and can't be empty".