Fix GetFilenamesAdvice double-firing and extend coverage to getParts(MultiMap) path

- jetty-appsec-9.3: add call-depth guard (Collection.class) to GetFilenamesAdvice
  to prevent double callback invocation when getParts() calls getParts(MultiMap) internally
- jetty-appsec-9.2: extend GetFilenamesAdvice matcher to all getParts overloads
  (not just no-arg) to cover getParameter*()/getParameterMap() code paths,
  guarded with same call-depth mechanism to avoid double-firing

Author: jandro996

dd-java-agent/instrumentation/jetty/jetty-appsec/jetty-appsec-8.1.3/src/main/java/datadog/trace/instrumentation/jetty8/RequestGetPartsInstrumentation.java

@@ -216,39 +216,41 @@ static void after(
       // Resolve getSubmittedFileName once (Servlet 3.1+; null on Servlet 3.0)
       Method getSubmittedFileName = null;
       try {
-        getSubmittedFileName =
-            parts.iterator().next().getClass().getMethod("getSubmittedFileName");
+        getSubmittedFileName = parts.iterator().next().getClass().getMethod("getSubmittedFileName");
       } catch (Exception ignored) {
       }
       List<String> filenames = new ArrayList<>();
-      for (Object part : parts) {
-        String name = null;
-        // Try Servlet 3.1+ API first (getSubmittedFileName)
-        if (getSubmittedFileName != null) {
+      if (getSubmittedFileName != null) {
+        // Servlet 3.1+: use getSubmittedFileName
+        for (Object part : parts) {
           try {
-            name = (String) getSubmittedFileName.invoke(part);
+            String name = (String) getSubmittedFileName.invoke(part);
+            if (name != null && !name.isEmpty()) {
+              filenames.add(name);
+            }
           } catch (Exception ignored) {
           }
         }
-        // Fallback: parse filename from Content-Disposition header (Servlet 3.0)
-        if (name == null) {
+      } else {
+        // Servlet 3.0: parse filename from Content-Disposition header
+        for (Object part : parts) {
           String cd = ((Part) part).getHeader("content-disposition");
           if (cd != null) {
             for (String tok : cd.split(";")) {
               tok = tok.trim();
               if (tok.startsWith("filename=")) {
-                name = tok.substring(9).trim();
+                String name = tok.substring(9).trim();
                 if (name.startsWith("\"") && name.endsWith("\"")) {
                   name = name.substring(1, name.length() - 1);
                 }
+                if (!name.isEmpty()) {
+                  filenames.add(name);
+                }
                 break;
               }
             }
           }
         }
-        if (name != null && !name.isEmpty()) {
-          filenames.add(name);
-        }
       }
       if (filenames.isEmpty()) {
         return;

dd-java-agent/instrumentation/jetty/jetty-appsec/jetty-appsec-9.2/src/main/java/datadog/trace/instrumentation/jetty92/RequestExtractContentParametersInstrumentation.java

@@ -52,8 +52,7 @@ public void methodAdvice(MethodTransformer transformer) {
             .and(takesArguments(1))
             .and(takesArgument(0, named("org.eclipse.jetty.util.MultiMap"))),
         getClass().getName() + "$GetPartsAdvice");
-    transformer.applyAdvice(
-        named("getParts").and(takesArguments(0)), getClass().getName() + "$GetFilenamesAdvice");
+    transformer.applyAdvice(named("getParts"), getClass().getName() + "$GetFilenamesAdvice");
   }
 
   private static final Reference REQUEST_REFERENCE =
@@ -144,12 +143,19 @@ static void after(
 
   @RequiresRequestContext(RequestContextSlot.APPSEC)
   public static class GetFilenamesAdvice {
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    static boolean before() {
+      return CallDepthThreadLocalMap.incrementCallDepth(Collection.class) == 0;
+    }
+
     @Advice.OnMethodExit(suppress = Throwable.class, onThrowable = Throwable.class)
     static void after(
+        @Advice.Enter boolean proceed,
         @Advice.Return Collection parts,
         @ActiveRequestContext RequestContext reqCtx,
         @Advice.Thrown(readOnly = false) Throwable t) {
-      if (t != null || parts == null || parts.isEmpty()) {
+      CallDepthThreadLocalMap.decrementCallDepth(Collection.class);
+      if (!proceed || t != null || parts == null || parts.isEmpty()) {
         return;
       }
       List<String> filenames = new ArrayList<>();

dd-java-agent/instrumentation/jetty/jetty-appsec/jetty-appsec-9.3/src/main/java/datadog/trace/instrumentation/jetty93/RequestExtractContentParametersInstrumentation.java

@@ -107,18 +107,24 @@ static void after(
 
   @RequiresRequestContext(RequestContextSlot.APPSEC)
   public static class GetFilenamesAdvice {
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    static boolean before() {
+      return CallDepthThreadLocalMap.incrementCallDepth(Collection.class) == 0;
+    }
+
     @Advice.OnMethodExit(suppress = Throwable.class, onThrowable = Throwable.class)
     static void after(
+        @Advice.Enter boolean proceed,
         @Advice.Return Collection parts,
         @ActiveRequestContext RequestContext reqCtx,
         @Advice.Thrown(readOnly = false) Throwable t) {
-      if (t != null || parts == null || parts.isEmpty()) {
+      CallDepthThreadLocalMap.decrementCallDepth(Collection.class);
+      if (!proceed || t != null || parts == null || parts.isEmpty()) {
         return;
       }
       Method getSubmittedFileName = null;
       try {
-        getSubmittedFileName =
-            parts.iterator().next().getClass().getMethod("getSubmittedFileName");
+        getSubmittedFileName = parts.iterator().next().getClass().getMethod("getSubmittedFileName");
       } catch (Exception ignored) {
       }
       if (getSubmittedFileName == null) {