public static boolean contains(CharSequence seq, CharSequence searchSeq) {
        if (seq == null || searchSeq == null) {
            return false;
        }
        return CharSequenceUtils.indexOf(seq, searchSeq, 0) >= 0;
    }
<p>Checks if CharSequence contains a search CharSequence, handling {@code null}.
This method uses {@link String#indexOf(String)} if possible.</p>

<p>A {@code null} CharSequence will return {@code false}.</p>

<pre>
StringUtils.contains(null, *)     = false
StringUtils.contains(*, null)     = false
StringUtils.contains("", "")      = true
StringUtils.contains("abc", "")   = true
StringUtils.contains("abc", "a")  = true
StringUtils.contains("abc", "z")  = false
</pre>

@param seq  the CharSequence to check, may be null
@param searchSeq  the CharSequence to find, may be null
@return true if the CharSequence contains the search CharSequence,
 false if not or {@code null} string input
@since 2.0
@since 3.0 Changed signature from contains(String, String) to contains(CharSequence, CharSequence)
android/android_framework/base/src/main/java/lang3/StringUtils.java