* @return reference to value to inject, or null if nothing should be injected
*/
protected Object getInjectionValue(final Field field) throws Exception {
// determine the value to inject
if (field.isAnnotationPresent(TestResource.class)) {
final TestResource resourceConfig = field.getAnnotation(TestResource.class);
final String resourceType = resourceConfig.value();
if (resourceType == null) {
throw new IllegalArgumentException("Null TestResource type '" + resourceType +
"' on field: " + clazz.getCanonicalName() + "." + field.getName());
} else {