Cannot upload traces when using an Jaeger sidecar

[c47gao]

Describe the bug
I used an Jaeger agent sidecar to collect traces. But it fails for some reason

Error Message
The jaeger agent sidecar itself is working properly and it's been used in other apps.

2021-06-29 20:40:04.014046 I | Endpoint has been deprecated. Please use CollectorEndpoint instead.
2021-06-29 20:40:04.020685 I | Starting application at port :3000
INFO[8:40PM]: incoming request	http-method=GET http-path=/readyz http-status=200 request-id=3b619ae1-0c2c-4c6a-8522-84366916ec0b 
2021-06-29 20:58:26.347798 I | Error when uploading spans to Jaeger: failed to upload traces; HTTP status code: 400

To Reproduce
Steps to reproduce the behavior:
Athens 0.11.0.

TraceExporter = "jaeger"

TraceExporterURL = "http://localhost:5778"

Jaeger agent sidecar uses the default setup:

{
                        "containerPort": 5775,
                        "protocol": "UDP"
},
{
                        "containerPort": 6831,
                        "protocol": "UDP"
},
{
                        "containerPort": 6832,
                        "protocol": "UDP"
 },
{
                        "containerPort": 5778,
                        "protocol": "TCP"
}

Expected behavior
Athens should be able to upload traces properly

Environment (please complete the following information):

• OS: [e.g. Linux 64bit]
• Go version : 1.16
• Proxy version : 0.11.0
• Storage (fs/mongodb/s3 etc.) : s3

Additional context
Add any other context about the problem here.

[arschles]

@c47gao are traces making it from Athens to the sidecar properly?