public static CIKey ofDynamicKey(final String dynamicKey) {
        if (dynamicKey == null) {
            return null;
        } else if (dynamicKey.isEmpty()) {
            return EMPTY_STRING;
        } else {
            return new CIKey(dynamicKey);
        }
    }
Create a {@link CIKey} for a key that is known NOT to be in {@link CIKey}s map
of common keys and is a key that will not be added to the map of common keys in future.
This is a minor optimisation that saves a map lookup if the key is known
to probably not be in the map.
<p>
Is null safe. If key is null, returns null.
</p>
stroom-util-shared/src/main/java/stroom/util/shared/string/CIKey.java