branding: keep Brand-Id papermc:paper for plugin compat, Brand-Name Delta

paper-server/build.gradle.kts

@@ -206,7 +206,10 @@ tasks.jar {
             "Specification-Title" to "Delta",
             "Specification-Version" to project.version,
             "Specification-Vendor" to "ZernMC",
-            "Brand-Id" to "zern:delta",
+            // Brand-Id stays papermc:paper on purpose: ServerBuildInfo#isBrandCompatible
+            // is what plugin/API compatibility checks key off. Brand-Name drives the
+            // client-visible brand (F3 "server: Delta"). Keep id stock, show Delta.
+            "Brand-Id" to "papermc:paper",
             "Brand-Name" to "Delta",
             "Build-Number" to (build ?: ""),
             "Build-Time" to buildTime.toString(),