Restore werror

Author: jack-berg

buildSrc/src/main/kotlin/otel.java-conventions.gradle.kts

@@ -87,7 +87,9 @@ tasks {
             // https://groups.google.com/forum/#!topic/bazel-discuss/_R3A9TJSoPM
             "-Xlint:-processing",
             // We suppress the "options" warning because it prevents compilation on modern JDKs
-            "-Xlint:-options"
+            "-Xlint:-options",
+            // Fail build on any warning
+            "-Werror",
           ),
         )
       }