make requestPayload also as JsonElement in LogData.

Author: zhumin8

gax-java/gax-grpc/src/main/java/com/google/api/gax/grpc/GrpcLoggingInterceptor.java

@@ -171,7 +171,7 @@ void logResponse(Status status, LogData.Builder logDataBuilder, Logger logger) {
   <RespT> void logRequestDetails(RespT message, LogData.Builder logDataBuilder) {
     try {
       if (LOGGER.isDebugEnabled()) {
-        logDataBuilder.requestPayload(GSON.toJson(message));
+        logDataBuilder.requestPayload(GSON.toJsonTree(message));
         Map<String, String> requestDetailsMap = logDataBuilder.build().toMapRequest();
         LoggingUtils.logWithMDC(
             LOGGER, Level.DEBUG, requestDetailsMap, "Sending gRPC request: request payload");

gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonLoggingInterceptor.java

@@ -183,7 +183,7 @@ void logResponse(int statusCode, LogData.Builder logDataBuilder, Logger logger)
   private <RespT> void logRequestDetails(RespT message, LogData.Builder logDataBuilder) {
     try {
       if (LOGGER.isDebugEnabled()) {
-        logDataBuilder.requestPayload(GSON.toJson(message));
+        logDataBuilder.requestPayload(GSON.toJsonTree(message));
         Map<String, String> requestDetailsMap = logDataBuilder.build().toMapRequest();
         LoggingUtils.logWithMDC(
             LOGGER, Level.DEBUG, requestDetailsMap, "Sending HTTP request: request payload");

gax-java/gax/src/main/java/com/google/api/gax/logging/LogData.java

@@ -56,7 +56,7 @@ public abstract class LogData {
   public abstract String requestHeaders();
 
   @Nullable
-  public abstract String requestPayload();
+  public abstract JsonElement requestPayload();
 
   @Nullable
   public abstract String responseStatus();
@@ -87,7 +87,7 @@ public abstract static class Builder {
 
     public abstract Builder requestHeaders(String requestHeaders);
 
-    public abstract Builder requestPayload(String requestPayload);
+    public abstract Builder requestPayload(JsonElement requestPayload);
 
     public abstract Builder responseStatus(String responseStatus);
 
@@ -119,7 +119,7 @@ public Map<String, String> toMapRequest() {
       map.put("request.headers", requestHeaders());
     }
     if (requestPayload() != null) {
-      map.put("request.payload", requestPayload());
+      map.put("request.payload", gson.toJson(requestPayload()));
     }
     if (httpMethod() != null) {
       map.put("request.method", httpMethod());