static String formatDataVarTemplate(String key) {
        return "$[" + key + ']';
    }
@Test
    public void givenKey_whenFormatDataVarTemplate_thenReturnTheSameStringAsFormat() {
        assertThat(TbNodeUtils.formatDataVarTemplate("key"), is("$[key]"));
        assertThat(TbNodeUtils.formatDataVarTemplate("key"), is(String.format(DATA_VARIABLE_TEMPLATE, "key")));

        assertThat(TbNodeUtils.formatDataVarTemplate(""), is("$[]"));
        assertThat(TbNodeUtils.formatDataVarTemplate(""), is(String.format(DATA_VARIABLE_TEMPLATE, "")));

        assertThat(TbNodeUtils.formatDataVarTemplate(null), is("$[null]"));
        assertThat(TbNodeUtils.formatDataVarTemplate(null), is(String.format(DATA_VARIABLE_TEMPLATE, (String) null)));
    }