code: public static List<String> split(@Nullable final String str, final char separatorChar) {
  		return split(str, separatorChar, 10);
  	}
docs: 高性能的Split，针对char的分隔符号，比JDK String自带的高效.
  
  copy from Commons Lange 3.5 StringUtils 并做优化
  
  @see #split(String, char, int)