[grid] Fix VNC caps not propagated for sessions without browserName (#17235)

Signed-off-by: Viet Nguyen Duc <nguyenducviet4496@gmail.com>

Author: VietND96

java/src/org/openqa/selenium/grid/node/config/SessionCapabilitiesMutator.java

@@ -46,10 +46,9 @@ public SessionCapabilitiesMutator(Capabilities slotStereotype) {
 
   @Override
   public Capabilities apply(Capabilities capabilities) {
-    if (!Objects.equals(slotStereotype.getBrowserName(), capabilities.getBrowserName())) {
-      return capabilities;
-    }
-
+    // Always propagate VNC capabilities from the stereotype, regardless of whether the session
+    // request included a browserName. Requests without browserName (e.g. proxy-only caps) are
+    // still routed to a slot that has VNC enabled, so the VNC address must be present.
     Object vncEnabled = slotStereotype.getCapability(SE_VNC_ENABLED);
     if (vncEnabled != null) {
       Object vncPort = slotStereotype.getCapability(SE_NO_VNC_PORT);
@@ -59,6 +58,10 @@ public Capabilities apply(Capabilities capabilities) {
               .setCapability(SE_NO_VNC_PORT, Require.nonNull(SE_NO_VNC_PORT, vncPort));
     }
 
+    if (!Objects.equals(slotStereotype.getBrowserName(), capabilities.getBrowserName())) {
+      return capabilities;
+    }
+
     String browserName = capabilities.getBrowserName().toLowerCase(Locale.ENGLISH);
 
     if ("internet explorer".equalsIgnoreCase(browserName)) {

java/test/org/openqa/selenium/grid/node/config/SessionCapabilitiesMutatorTest.java

@@ -343,6 +343,26 @@ void shouldMergeTopLevelStereotypeAndCaps() {
     assertThat(modifiedCapabilities.get("pageLoadStrategy")).isEqualTo("normal");
   }
 
+  @Test
+  void shouldPropagateVncCapsWhenRequestHasNoBrowserName() {
+    // Requests without browserName (e.g. proxy-only caps) are still routed to a VNC-enabled slot;
+    // the VNC address must be present in the merged capabilities.
+    Capabilities stereotype =
+        new ImmutableCapabilities(
+            "browserName", "chrome", "se:vncEnabled", true, "se:noVncPort", 7900);
+
+    SessionCapabilitiesMutator sessionCapabilitiesMutator =
+        new SessionCapabilitiesMutator(stereotype);
+
+    Capabilities capabilities = new ImmutableCapabilities("proxy", Map.of("proxyType", "direct"));
+
+    Map<String, Object> modifiedCapabilities =
+        sessionCapabilitiesMutator.apply(capabilities).asMap();
+
+    assertThat(modifiedCapabilities.get("se:vncEnabled")).isEqualTo(true);
+    assertThat(modifiedCapabilities.get("se:noVncPort")).isEqualTo(7900);
+  }
+
   @Test
   void shouldAllowUnknownBrowserNames() {
     Capabilities stereotype = new ImmutableCapabilities("browserName", "safari");