json - Grails 3.2.9: ペイロード処理例外を与える Rest Assured を使用した Spring Rest Docs: com.fasterxml.jackson.core.JSONParseException

Question

Rest Assured を使用して、Spring Rest ドキュメントを Grails 3.2.9 アプリケーションと統合しようとしています。統合テスト中に、ペイロード処理例外が生成されます。

完全なスタック トレース:

org.springframework.restdocs.payload.PayloadHandlingException: com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
 at [Source: [B@793cd42d; line: 1, column: 2]
    at org.springframework.restdocs.payload.JsonContentHandler.readContent(JsonContentHandler.java:84)
    at org.springframework.restdocs.payload.JsonContentHandler.findMissingFields(JsonContentHandler.java:50)
    at org.springframework.restdocs.payload.AbstractFieldsSnippet.validateFieldDocumentation(AbstractFieldsSnippet.java:113)
    at org.springframework.restdocs.payload.AbstractFieldsSnippet.createModel(AbstractFieldsSnippet.java:74)
    at org.springframework.restdocs.snippet.TemplatedSnippet.document(TemplatedSnippet.java:64)
    at org.springframework.restdocs.generate.RestDocumentationGenerator.handle(RestDocumentationGenerator.java:192)
    at org.springframework.restdocs.restassured.RestDocumentationFilter.filter(RestDocumentationFilter.java:63)
    at com.jayway.restassured.internal.filter.FilterContextImpl.next(FilterContextImpl.groovy:73)
    at org.springframework.restdocs.restassured.RestAssuredRestDocumentationConfigurer.filter(RestAssuredRestDocumentationConfigurer.java:65)
    at com.jayway.restassured.internal.filter.FilterContextImpl.next(FilterContextImpl.groovy:73)
    at com.jayway.restassured.internal.RequestSpecificationImpl.applyPathParamsAndSendRequest(RequestSpecificationImpl.groovy:1574)
    at com.jayway.restassured.internal.RequestSpecificationImpl.get(RequestSpecificationImpl.groovy:159)
    at so.con.BaseRestDocTestSetup.$tt__createDoc(BaseRestDocTestSetup.groovy:130)
    at so.con.BaseRestDocTestSetup.createDoc_closure4(BaseRestDocTestSetup.groovy)
    at groovy.lang.Closure.call(Closure.java:414)
    at groovy.lang.Closure.call(Closure.java:430)
    at grails.transaction.GrailsTransactionTemplate$1.doInTransaction(GrailsTransactionTemplate.groovy:70)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133)
    at grails.transaction.GrailsTransactionTemplate.executeAndRollback(GrailsTransactionTemplate.groovy:67)
    at so.con.v1.docs.ConfApiDocSpec.test and document get request for /conf getting conf-list as Response(ConfApiDocSpec.groovy:63)
Caused by: com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
 at [Source: [B@793cd42d; line: 1, column: 2]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1702)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:558)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:456)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._handleUnexpectedValue(UTF8StreamJsonParser.java:2689)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._nextTokenNotInObject(UTF8StreamJsonParser.java:878)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:772)
    at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:3834)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3783)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2929)
    at org.springframework.restdocs.payload.JsonContentHandler.readContent(JsonContentHandler.java:81)
    ... 19 more

これを解決するのを手伝ってください。