public static int indexOfIgnoreCase(CharSequence str, CharSequence searchStr) {
        return indexOfIgnoreCase(str, searchStr, 0);
    }
<p>Case in-sensitive find of the first index within a CharSequence.</p>

<p>A {@code null} CharSequence will return {@code -1}.
A negative start position is treated as zero.
An empty ("") search CharSequence always matches.
A start position greater than the string length only matches
an empty search CharSequence.</p>

<pre>
StringUtils.indexOfIgnoreCase(null, *)          = -1
StringUtils.indexOfIgnoreCase(*, null)          = -1
StringUtils.indexOfIgnoreCase("", "")           = 0
StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1
</pre>

@param str  the CharSequence to check, may be null
@param searchStr  the CharSequence to find, may be null
@return the first index of the search CharSequence,
 -1 if no match or {@code null} string input
@since 2.5
@since 3.0 Changed signature from indexOfIgnoreCase(String, String) to indexOfIgnoreCase(CharSequence, CharSequence)
android/android_framework/base/src/main/java/lang3/StringUtils.java