Per the spec re: Endpoint URLs for OTLP/HTTP, when the non-per-signal endpoint env var (OTEL_EXPORTER_OTLP_ENDPOINT) is set, the exporter must construct per-signal URLs (either v1/traces or v1/metrics).

Currently, the exporter does not do this; v1/traces must be manually added to the end point when setting only OTEL_EXPORTER_OTLP_ENDPOINT. Not doing so produces a 404 error when attempting to export spans.