public static String getSimpleClassName(String fullName) {
    return fullName.substring(fullName.lastIndexOf('/') + 1);
  }
Return {@code true} if, and only if identifier passed is compliant to JLS9 section 3.8 AND DOES NOT CONTAINS so-called "ignorable" characters.
Ignorable characters are removed by javac silently during compilation and thus may appear only in specially crafted obfuscated classes.
For more information about "ignorable" characters see <a href="https://bugs.openjdk.java.net/browse/JDK-7144981">JDK-7144981</a>.

@param identifier Identifier to be checked
@return {@code true} in case {@code identifier} passed can be used as an identifier; {@code false} otherwise.
src/org/jetbrains/java/decompiler/modules/renamer/ConverterHelper.java