code: public static String afterPrefixIgnoreCase(String string, String prefix) {
  		if (string.length() < prefix.length()) {
  			return null;
  		}
  
  		for (int i = 0; i < prefix.length(); i++) {
  			char a = Character.toUpperCase(prefix.charAt(i));
  			char b = Character.toUpperCase(string.charAt(i));
  			if (a != b) {
  				return null;
  			}
  		}
  
  		return string.substring(prefix.length());
  	}
docs: <p>
  Returns a substring of the given string that comes after the given
  prefix. Prefix matching is case-insensitive.
  </p>
  <p>
  <b>Example:</b>
  </p>
  
  <pre class="brush:java">
  String result = StringUtils.afterPrefixIgnoreCase("MAILTO:email@example.com", "mailto:");
  assertEquals("email@example.com", result);
  
  result = StringUtils.afterPrefixIgnoreCase("http://www.google.com", "mailto:");
  assertNull(result);
  </pre>
  
  @param string the string
  @param prefix the prefix
  @return the string or null if the prefix was not found