Re-factor ConcurrentModificationException re-wrapping

[andrii-kovalenko-ct]

Situation
PaymentMethodDispatcher itself throws io.sphere.sdk.client.ConcurrentModificationException

Complication
in PaymentDispatcher#dispatchPayment():

try {
    return methodDispatcher.dispatchPayment(paymentWithCartLike);
} catch (final ConcurrentModificationException cme) {
    throw new java.util.ConcurrentModificationException
        ("The payment could not be dispatched: " + cme.getMessage(), cme);
}

The thrown io.sphere.sdk.client.ConcurrentModificationException is wrapped to java.util.ConcurrentModificationException exception, which is unnecessary and make developer confusing.

Resolution

• Avoid wrapping into java.util.ConcurrentModificationException
• Fix the caller in PaymentHandler.java, which catches java.util.ConcurrentModificationException now.
• Fix corresponding test cases if any.

Additional Information
#159 (comment)

After this #166 should be fixed