Create Session => Content-Type is unsupported. You should use application/json instead

[vorburger]

https://github.com/clerk/clerk-sdk-java/blob/main/docs/sdks/sessions/README.md#create causes:

"Content-Type is unsupported","long_message":"Content-Type is unsupported. You should use application/json instead.",

ClerksTest > clerkTestingToken() FAILED
    SDKError[requestMethod=POST, requestUri=https://api.clerk.com/v1/sessions/sess_39zfw909Yvg9iEfgxVGM1IC3iDf/tokens, code=415, responseHeaders={:status=[415], cf-cache-status=[DYNAMIC], cf-ray=[9d18d52f1b327a85-ZRH], clerk-api-version=[2025-11-10], content-length=[228], content-type=[application/json], date=[Sat, 21 Feb 2026 20:00:56 GMT], server=[cloudflare], set-cookie=[__cf_bm=n3QrywajChUuzq95LHZs9LQEGEAbiBUXSOnsvYOzg7E-1771704056-1.0.1.1-2Cbe4GAqRt42WHTgNj.ovn4H2GxUhfdHN_hWRcVpP1gGK49gGr_70K97pYTlGZ3GQbzi0uqCtHDIfHWH_XdCE1PdEMlXa0IpI83kYHZvyXE; path=/; expires=Sat, 21-Feb-26 20:30:56 GMT; domain=.api.clerk.com; HttpOnly; Secure; SameSite=None, _cfuvid=SClopz.8P6zvAeeE1aAfZADl7YHmmvqBWnJxWe0nv1c-1771704056345-0.0.1.1-604800000; path=/; domain=.api.clerk.com; HttpOnly; Secure; SameSite=None], x-cfworker=[1], x-clerk-trace-id=[ba15286b6af46c65de478848a7c3cb1f], x-cloud-trace-context=[ba15286b6af46c65de478848a7c3cb1f]}, message=API error occurred, body={"errors":[{"message":"Content-Type is unsupported","long_message":"Content-Type  is unsupported. You should use application/json instead.","code":"unsupported_content_type"}],"clerk_trace_id":"ba15286b6af46c65de478848a7c3cb1f"}]
        at app//com.clerk.backend_api.models.errors.SDKError.from(SDKError.java:35)
        at app//com.clerk.backend_api.models.errors.SDKError.from(SDKError.java:29)
        at app//com.clerk.backend_api.operations.CreateSessionToken$Sync.handleResponse(CreateSessionToken.java:217)
        at app//com.clerk.backend_api.operations.CreateSessionToken$Sync.handleResponse(CreateSessionToken.java:133)
        at app//com.clerk.backend_api.models.operations.CreateSessionTokenRequestBuilder.call(CreateSessionTokenRequestBuilder.java:77)
        at app//dev.enola.common.auth.clerk.Clerks.clerkTestingToken(Clerks.java:100)
        at app//dev.enola.common.auth.clerk.ClerksTest.clerkTestingToken(ClerksTest.java:14)

from:

public static String clerkTestingToken() {
        Clerk clerk = Clerk.builder().bearerAuth(CLERK_SECRET_KEY).build();
        var testUserID = "user_...";
        var sessionID =
                clerk.sessions()
                        .create()
                        .request(new CreateSessionRequestBody(testUserID))
                        .call()
                        .session()
                        .get()
                        .id();
        return clerk.sessions()
                .createToken()
                .sessionId(sessionID)
                .call()
                .object()
                .get()
                .jwt()
                .get();
        // TODO Return a Closeable where close() revokes the token
    }

Intended to be use in an integration test.

[vorburger]

Ah, this can be worked around with an empty CreateSessionTokenRequestBody.

That resolves the Clerk SDK's 415 response by ensuring it sets the Content-Type: application/json header correctly.

        return clerk.sessions()
                .createToken()
                .sessionId(sessionID)
                .requestBody(new CreateSessionTokenRequestBody())
                .call()
                .object()
                .get()
                .jwt()
                .get();

It works, but seems a bit surprising that this is required - perhaps this should be made the default?