19742 Enforce TLS when setting basic authentication for OTel Collector

Validate that TLS encryption is enabled whenever basic authentication
is selected for GRPC/HTTP protocols, in both the GUI form and REST API.
CMK-33249

Change-Id: Ic1276fee891a5aac19f2d829bee75f077e1ae686

Author: m3hransh

.werks/19742.md

@@ -0,0 +1,22 @@
+[//]: # (werk v3)
+# Enforce TLS when using basic authentication for OTel Collector receivers
+
+key        | value
+---------- | ---
+date       | 2026-04-09T16:36:29.851214+00:00
+version    | 2.6.0b1
+class      | feature
+edition    | ultimate
+component  | wato
+level      | 1
+compatible | no
+
+Checkmk now validates that TLS encryption is enabled whenever basic authentication
+is configured for OpenTelemetry Collector receiver endpoints (GRPC and HTTP).
+
+Previously, it was possible to configure basic authentication without encryption,
+which would transmit credentials in plain text. The GUI setup and REST API now
+reject this combination and require you to enable TLS first.
+
+If you have existing receiver configurations using basic authentication without TLS,
+you will need to enable TLS encryption before you can save any changes to them.