code: public PactDslJsonArray valueFromProviderState(String expression, Object example) {
      generators.addGenerator(Category.BODY, rootPath + appendArrayIndex(0), new ProviderStateGenerator(expression));
      body.put(example);
      return this;
    }
docs: Adds an element that will have it's value injected from the provider state
  @param expression Expression to be evaluated from the provider state
  @param example Example value to be used in the consumer test