private boolean isNonAllowedNegativeNumber(BigInteger value) {
		if (value == null) {
			return false;
		}
		if (allowsNegative) {
			return false;
		}

		// so we don't allow negatives
		return value.signum() < 0;
	}
DocumentFilter that prevents users from entering invalid data into the field.
Ghidra/Framework/Docking/src/main/java/docking/widgets/textfield/IntegerTextField.java