public static Field findFieldIfExists(Class<?> clazz, String fieldName) {
        try {
            return findField(clazz, fieldName);
        } catch (NoSuchFieldError e) {
            return null;
        }
    }
Look up and return a field if it exists.
Like {@link #findField}, but doesn't throw an exception if the field doesn't exist.

@param clazz     The class which either declares or inherits the field.
@param fieldName The field name.
@return A reference to the field, or {@code null} if it doesn't exist.
android/android_framework/base/src/main/java/util/XposedHelpers.java