code: @Nullable
      public static String classToSignature(String className) {
          if (className == null) {
              return null;
          } else if (className.startsWith(Values.SIG_ARRAY_PREFIX)) {
              // convert the classname inside the array
              return Values.SIG_ARRAY_PREFIX + classToSignature(className.substring(Values.SIG_ARRAY_PREFIX.length()));
          } else if (PRIMITIVE_TYPES.contains(className) || className.endsWith(Values.SIG_QUALIFIED_CLASS_SUFFIX)) {
              return className.replace('.', '/');
          } else {
              String primitive = PRIMITIVE_NAME_TO_SIG.get(className);
              if (primitive != null) {
                  return primitive;
              }
  
              return Values.SIG_QUALIFIED_CLASS_PREFIX + className.replace('.', '/') + Values.SIG_QUALIFIED_CLASS_SUFFIX_CHAR;
          }
      }
docs: returns a slashed or dotted class name into a signature, like java/lang/String -- Ljava/lang/String; Primitives and arrays are accepted.
  
  @param className
  the class name to convert
  @return the signature format of the class