Add missing json() invocation in JsonFieldPathsTests

See gh-720

Author: izeye

spring-restdocs-core/src/test/java/org/springframework/restdocs/payload/JsonFieldPathsTests.java

@@ -80,7 +80,7 @@ public void missingEntriesInNestedMapAreIdentifiedAsUncommon() {
 public void absentItemFromFieldExtractionCausesAllPresentFieldsToBeIdentifiedAsUncommon() {
 assertThat(
 JsonFieldPaths
-.from(Arrays.asList(ExtractedField.ABSENT, ("{\"a\": 1, \"b\": {\"c\": 1}}"),
+.from(Arrays.asList(ExtractedField.ABSENT, json("{\"a\": 1, \"b\": {\"c\": 1}}"),
 json("{\"a\": 1, \"b\": {\"c\": 1}}"), json("{\"a\": 1, \"b\": {\"d\": 2}}")))
 .getUncommon()).containsExactly("", "a", "b", "b.c", "b.d");
 }