src/main/java/com/github/wnameless/json/unflattener/JsonUnflattener.java
public JsonUnflattener withLeftAndRightBrackets(char leftBracket,
      char rightBracket) {
    isTrue(leftBracket != rightBracket, "Both brackets cannot be the same");
    isTrue(!Character.toString(leftBracket).matches(illegalBracketsRegex()),
        "Left bracket contains illegal chracter(%s)",
        Character.toString(leftBracket));
    isTrue(!Character.toString(rightBracket).matches(illegalBracketsRegex()),
        "Right bracket contains illegal chracter(%s)",
        Character.toString(rightBracket));

    this.leftBracket = leftBracket;
    this.rightBracket = rightBracket;
    return this;
  }
public JsonUnflattener withLeftAndRightBrackets(char leftBracket,
      char rightBracket) {
    isTrue(leftBracket != rightBracket, "Both brackets cannot be the same");
    isTrue(!Character.toString(leftBracket).matches(illegalBracketsRegex()),
        "Left bracket contains illegal chracter(%s)",
        Character.toString(leftBracket));
    isTrue(!Character.toString(rightBracket).matches(illegalBracketsRegex()),
        "Right bracket contains illegal chracter(%s)",
        Character.toString(rightBracket));

    this.leftBracket = leftBracket;
    this.rightBracket = rightBracket;
    return this;
  }
A fluent setter to setup the left and right brackets within a key in the
flattened JSON. The default left and right brackets are left square
bracket([) and right square bracket(]).

@param leftBracket
any character
@param rightBracket
any character
@return this {@link JsonUnflattener}