core/src/main/java/org/springframework/security/core/parameters/AnnotationParameterNameDiscoverer.java
private <T extends AccessibleObject> String[] lookupParameterNames(
			ParameterNameFactory<T> parameterNameFactory, T t) {
		Annotation[][] parameterAnnotations = parameterNameFactory.findParameterAnnotations(t);
		int parameterCount = parameterAnnotations.length;
		String[] paramNames = new String[parameterCount];
		boolean found = false;
		for (int i = 0; i < parameterCount; i++) {
			Annotation[] annotations = parameterAnnotations[i];
			String parameterName = findParameterName(annotations);
			if (parameterName != null) {
				found = true;
				paramNames[i] = parameterName;
			}
		}
		return found ? paramNames : null;
	}
private <T extends AccessibleObject> String[] lookupParameterNames(
			ParameterNameFactory<T> parameterNameFactory, T t) {
		Annotation[][] parameterAnnotations = parameterNameFactory.findParameterAnnotations(t);
		int parameterCount = parameterAnnotations.length;
		String[] paramNames = new String[parameterCount];
		boolean found = false;
		for (int i = 0; i < parameterCount; i++) {
			Annotation[] annotations = parameterAnnotations[i];
			String parameterName = findParameterName(annotations);
			if (parameterName != null) {
				found = true;
				paramNames[i] = parameterName;
			}
		}
		return found ? paramNames : null;
	}
Gets the parameter names or null if not found.

@param parameterNameFactory the {@link ParameterNameFactory} to use
@param t the {@link AccessibleObject} to find the parameter names on (i.e. Method
or Constructor)
@return the parameter names or null