code: public static String concat(String[] parts, char character) {
      StringBuilder stringBuilder = new StringBuilder();
  
      for (String part : parts) {
        stringBuilder.append(part).append(character);
      }
  
      stringBuilder.deleteCharAt(stringBuilder.length() - 1);
  
      return stringBuilder.toString();
    }
docs: String concatenation helper method.
  
  @param parts     String parts.
  @param character Separation character.
  @return A string.