Use JsonProperty for non-attribute members in XML models

[RikkiGibson]

This fixes a regression related to headers serialization. When you use @JacksonXmlProperty, the attribute values are ignored for JSON serialization, but when you use @JsonProperty, the attribute values are also used for XML serialization.

Since we do JSON serialization internally to translate to Headers classes, we weren't serializing using the correct header names, and we would always produce a Headers object with null for every property.

This fix was only tested manually against a Blob Service Swagger because it's been requested that this fix be deployed ASAP.

[olydis]

🤖 AutoRest automatic feature coverage report 🤖

feature set version 2.3.14

❌️ General: 92%

40 out of 522 features are not covered by tests

ConstantsInBody, ConstantsInPath, FileStreamVeryLarge, FormdataStreamUploadFile, HttpRedirect300Get, HttpRedirect300Head, HttpRedirect301Get, HttpRedirect301Put, HttpRedirect302Get, HttpRedirect302Head, HttpRedirect302Patch, HttpRedirect303Post, HttpRedirect307Delete, HttpRedirect307Get, HttpRedirect307Head, HttpRedirect307Patch, HttpRedirect307Post, HttpRedirect307Put, ResponsesScenarioC200MatchingModel, ResponsesScenarioC201MatchingModel, ResponsesScenarioC404MatchingModel, StreamUploadFile, UrlPathsArrayCSVInPath, UrlQueriesArrayMultiEmpty, UrlQueriesArrayMultiNull, UrlQueriesArrayMultiValid, allowedValueEnum, expectedEnum, getByteEmpty, getByteInvalid, getComplexPolymorphismComplicated, getEnumReferenced, getEnumReferencedConstant, getStringMultiByteCharacters, putComplexPolymorphismComplicated, putEnumReferenced, putEnumReferencedConstant, putStringMultiByteCharacters, roundTripEnum, unexpectedEnum

❌️ Azure: 88%

14 out of 118 features are not covered by tests

AzureMethodQueryUrlEncoding, AzureODataFilter, AzurePathQueryUrlEncoding, AzureRequestClientIdInError, AzureSwaggerQueryUrlEncoding, AzureXmsCustomNamedRequestId, AzureXmsCustomNamedRequestIdParameterGroup, AzureXmsRequestClientIdNull, CustomHeaderPostAsyncSucceded, CustomHeaderPostSucceeded, CustomHeaderPutAsyncSucceded, CustomHeaderPutSucceeded, LRONonRetryPut201Creating400InvalidJson, PagingOdataMultiple