public static Callback dummyIfNull(Callback c) {
		if (c == null) {
			return dummy();
		}
		return c;
	}
Returns the given callback object if it is not <code>null</code>.  Otherwise, a {@link #dummy()} 
callback is returned.  This is useful to avoid using <code>null</code>.

@param c the callback function to check for <code>null</code>
@return a non-null callback function
Ghidra/Framework/Utility/src/main/java/utility/function/Callback.java