[BUG] Duplicated field "client" in BlockBlobClient, raises gson IllegalArgumentException

[rcomar-cit]

Describe the bug

• I created a simple function app to learn about blob triggers, following this reference Azure Blob storage trigger for Azure Functions
• I'm trying to create a Function App to be triggered by blob storage events, and would like to retrieve the file metadata fields to use as parameters to file processing logic.
• But when I declare @BlobTrigger in a BlobClient blobClient, raises the exception below. If I change to String content (or byte[]) the trigger works as expected.
• I tried to remove gson as a indirect dependency in pom.xml, also tried to declare jackson to be the default serialized, but no success.
• I managed to create by hand the blobClient and reach the file metadata, but I think that's not the right approach.

Exception or Stack Trace

Executing 'Functions.processBlob' (Reason='New blob detected(LogsAndContainerScan): my_blob_storage/my_folder/my_file.csv', Id=bb2845c7-9d8c-4ecd-b6e0-21b42b73a345)
[2025-07-09T20:58:04.183Z] Trigger Details: MessageId: 28459ab1-e4de-4c2d-9bfb-901df92c32de, DequeueCount: 1, InsertedOn: 2025-07-09T20:58:03.000+00:00, BlobCreated: 2025-07-09T17:55:50.000+00:00, BlobLastModified: 2025-07-09T20:58:02.000+00:00
[2025-07-09T20:58:04.209Z] Executed 'Functions.processBlob' (Failed, Id=bb2845c7-9d8c-4ecd-b6e0-21b42b73a345, Duration=30ms)
[2025-07-09T20:58:04.209Z] System.Private.CoreLib: Exception while executing function: Functions.processBlob. System.Private.CoreLib: Result: Failure
[2025-07-09T20:58:04.209Z] Exception: IllegalArgumentException: Class com.azure.storage.blob.specialized.BlockBlobClient declares multiple JSON fields named 'client'; conflict is caused by fields com.azure.storage.blob.specialized.BlockBlobClient#client and com.azure.storage.blob.specialized.BlobClientBase#client
[2025-07-09T20:58:04.209Z] See https://github.com/google/gson/blob/main/Troubleshooting.md#duplicate-fields
[2025-07-09T20:58:04.210Z] Stack: java.lang.IllegalArgumentException: Class com.azure.storage.blob.specialized.BlockBlobClient declares multiple JSON fields named 'client'; conflict is caused by fields com.azure.storage.blob.specialized.BlockBlobClient#client and com.azure.storage.blob.specialized.BlobClientBase#client
[2025-07-09T20:58:04.210Z] See https://github.com/google/gson/blob/main/Troubleshooting.md#duplicate-fields
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createDuplicateFieldException(ReflectiveTypeAdapterFactory.java:313)
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:409)
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:161)
[2025-07-09T20:58:04.210Z]      at com.google.gson.Gson.getAdapter(Gson.java:628)
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:201)
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:395)
[2025-07-09T20:58:04.210Z]      at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:161)
[2025-07-09T20:58:04.210Z]      at com.google.gson.Gson.getAdapter(Gson.java:628)
[2025-07-09T20:58:04.211Z]      at com.google.gson.Gson.fromJson(Gson.java:1360)
[2025-07-09T20:58:04.211Z]      at com.google.gson.Gson.fromJson(Gson.java:1262)
[2025-07-09T20:58:04.211Z]      at com.google.gson.Gson.fromJson(Gson.java:1171)
[2025-07-09T20:58:04.211Z]      at com.google.gson.Gson.fromJson(Gson.java:1137)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.DataOperations.convertFromJson(DataOperations.java:158)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.DataOperations.apply(DataOperations.java:114)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.DataSource.computeByType(DataSource.java:56)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.RpcStringDataSource.computeByType(RpcStringDataSource.java:5)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.DataSource.computeByName(DataSource.java:42)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.RpcStringDataSource.computeByName(RpcStringDataSource.java:5)
[2025-07-09T20:58:04.211Z]      at com.microsoft.azure.functions.worker.binding.BindingDataStore.getDataByName(BindingDataStore.java:66)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.binding.ExecutionContextDataSource.getBindingData(ExecutionContextDataSource.java:181)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolve(ParameterResolver.java:44)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.broker.ParameterResolver.resolveArguments(ParameterResolver.java:22)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.broker.EnhancedJavaMethodExecutorImpl.execute(EnhancedJavaMethodExecutorImpl.java:20)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.chain.FunctionExecutionMiddleware.invoke(FunctionExecutionMiddleware.java:19)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.chain.InvocationChain.doNext(InvocationChain.java:21)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.broker.JavaFunctionBroker.invokeMethod(JavaFunctionBroker.java:195)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:34)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.handler.InvocationRequestHandler.execute(InvocationRequestHandler.java:10)
[2025-07-09T20:58:04.212Z]      at com.microsoft.azure.functions.worker.handler.MessageHandler.handle(MessageHandler.java:44)
[2025-07-09T20:58:04.213Z]      at com.microsoft.azure.functions.worker.JavaWorkerClient$StreamingMessagePeer.lambda$onNext$0(JavaWorkerClient.java:94)
[2025-07-09T20:58:04.213Z]      at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
[2025-07-09T20:58:04.213Z]      at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[2025-07-09T20:58:04.213Z]      at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[2025-07-09T20:58:04.213Z]      at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[2025-07-09T20:58:04.213Z]      at java.base/java.lang.Thread.run(Thread.java:840)

To Reproduce

• Create a simple function app in java, with blob trigger
• Declare a method with @BlobTrigger annotation to BlobClient variable
• Start the function app and upload a file to the monitoring folder

Code Snippet

public class FunctionTriggers {

@FunctionName("processBlob")
    public void run(
           @BlobTrigger(name = "content", path = "my_blob_storage/my_folder/{fileName}", connection = "SourceBlogStorageConnStr") BlobClient blobClient,
            @BindingName("fileName") String fileName,
            ExecutionContext ctx) {

        ctx.getLogger().info("Size = " + blobClient.getProperties().getBlobSize());
        ctx.getLogger().info("Filename = " + fileName);
        ctx.getLogger().info("Metadata = " + blobClient.getProperties().getMetadata().entrySet());
    }
}

Expected behavior

• Code runs sucessfully, just like it expected.

Setup (please complete the following information):

• OS: Darwin arm64 24.5.0
• IDE: VS Code 1.101.0
  Commit: dfaf44141ea9deb3b4096f7cd6d24e00c147a4b1
  Date: 2025-06-11T15:00:50.123Z
  Electron: 35.5.1
  ElectronBuildId: 11727614
  Chromium: 134.0.6998.205
  Node.js: 22.15.1
  V8: 13.4.114.21-electron.0
• Library/Libraries: azure-storage-blob : 12.28.0
• Library/Libraries: azure-functions-java-library : 3.1.0
• Java version: 17
• App Server/Environment: Azure Function
• Frameworks: Guice 5.1.0