### Question:
AptUtils { public static String linkToKey( String text ) { int length = text.length(); StringBuilder buffer = new StringBuilder( length ); for ( int i = 0; i < length; ++i ) { char c = text.charAt( i ); if ( Character.isLetterOrDigit( c ) ) { buffer.append( Character.toLowerCase( c ) ); } } return buffer.toString(); } private  AptUtils(); static String encodeFragment( String text ); static boolean isExternalLink( String link ); static boolean isInternalLink( String link ); static boolean isLocalLink( String link ); static String linkToKey( String text ); static String encodeAnchor( String id );  }### Answer:
@SuppressWarnings( "deprecation" ) @Test public void testLinkToKey() { assertEquals( "abc56au", AptUtils.linkToKey( "aB$%C56 a&\\/'U" ) ); }