public static <T extends Comparable<? super T>> int compare(T c1, T c2) {
        return compare(c1, c2, false);
    }
<p>Null safe comparison of Comparables.
{@code null} is assumed to be less than a non-{@code null} value.</p>

@param <T> type of the values processed by this method
@param c1  the first comparable, may be null
@param c2  the second comparable, may be null
@return a negative value if c1 < c2, zero if c1 = c2
 and a positive value if c1 > c2
android/android_framework/base/src/main/java/lang3/ObjectUtils.java