The documentation for in the XSD for the queue-length on the managed-executor-service states:

A managed executor service (implementing javax.enterprise.concurrent.ManagedExecutorService).
If the "thread-factory" attribute is not defined a managed thread factory with no context service and normal thread priority will be created and used by the executor.
The task queue is based on the values of "core-threads" and "queue-length":

• If "queue-length" is 0, or "queue-length" is Integer.MAX_VALUE (2147483647) and "core-threads" is 0, direct handoff queuing strategy will be used and a SynchronousQueue will be created.
• If "queue-length" is Integer.MAX_VALUE but "core-threads" is not 0, an unbounded queue will be used.
• For any other valid value for "queue-length", a bounded queue wil be created.

The model description states:

The executors task queue capacity. A length of 0 means direct hand-off and possible rejection will occur. An undefined length (the default), or Integer.MAX_VALUE, indicates that an unbounded queue should be used. All other values specify an exact queue size. If an unbounded queue or direct hand-off is used, a core-threads value greater than zero is required.

The two descriptions should match. The model validation should also be checked as one of the messages doesn't seem to be correct:

// Validate an unbounded queue
if (!queueLength.isDefined() || queueLength.asInt() == Integer.MAX_VALUE) {
    if (coreThreads.isDefined() && coreThreads.asInt() <= 0) {
        throw EeLogger.ROOT_LOGGER.invalidCoreThreadsSize(coreThreads.asString());
    }

}

That message doesn't really describe the real problem and will always be

WFLYEE0112: The core-threads value must be greater than 0 when the queue-length is 0