code: @Nonnull
    public static char [] replaceMultiple (@Nullable final String sInputString,
                                           @Nonnull final char [] aSearchChars,
                                           final char cReplacementChar)
    {
      ValueEnforcer.notNull (aSearchChars, "SearchChars");
  
      // Any input text?
      if (hasNoText (sInputString))
        return ArrayHelper.EMPTY_CHAR_ARRAY;
  
      // Get char array
      final char [] aInput = sInputString.toCharArray ();
  
      // Any replacement patterns?
      if (aSearchChars.length == 0)
        return aInput;
  
      // build result
      final char [] aOutput = new char [aInput.length];
      int nOutputIndex = 0;
      for (final char c : aInput)
      {
        if (ArrayHelper.contains (aSearchChars, c))
          aOutput[nOutputIndex] = cReplacementChar;
        else
          aOutput[nOutputIndex] = c;
        nOutputIndex++;
      }
      return aOutput;
    }
docs: Optimized replace method that replaces a set of characters with another
  character. This method was created for efficient unsafe character
  replacements!
  
  @param sInputString
  The input string.
  @param aSearchChars
  The characters to replace.
  @param cReplacementChar
  The new char to be used instead of the search chars.
  @return The replaced version of the string or an empty char array if the
  input string was <code>null</code>.