github
@@ -48,6 +48,7 @@ export enum Feature {
   ExportDiagnosticsEnabled = "export_diagnostics_enabled",
   IgnoreGeneratedFiles = "ignore_generated_files",
   ImprovedProxyCertificates = "improved_proxy_certificates",
+  JavaNetworkDebugging = "java_network_debugging",
   OverlayAnalysis = "overlay_analysis",
   OverlayAnalysisActions = "overlay_analysis_actions",
   OverlayAnalysisCodeScanningActions = "overlay_analysis_code_scanning_actions",
@@ -174,6 +175,11 @@ export const featureConfig = {
     envVar: "CODEQL_ACTION_IMPROVED_PROXY_CERTIFICATES",
     minimumVersion: undefined,
   },
+  [Feature.JavaNetworkDebugging]: {
+    defaultValue: false,
+    envVar: "CODEQL_ACTION_JAVA_NETWORK_DEBUGGING",
+    minimumVersion: undefined,
+  },
   [Feature.OverlayAnalysis]: {
     defaultValue: false,
     envVar: "CODEQL_ACTION_OVERLAY_ANALYSIS",

@@ -95,6 +95,7 @@ import {
   BuildMode,
   GitHubVersion,
   Result,
+  getOptionalEnvVar,
 } from "./util";
 import { checkWorkflow } from "./workflow";
 
@@ -753,6 +754,19 @@ async function run(startedAt: Date) {
       }
     }
 
+    // Enable Java network debugging if the FF is enabled.
+    if (await features.getValue(Feature.JavaNetworkDebugging)) {
+      // Get the existing value of `JAVA_OPTS`, if any.
+      const existingJavaToolOptions =
+        getOptionalEnvVar("JAVA_TOOL_OPTIONS") || "";
+
+      // Add the network debugging options.
+      core.exportVariable(
+        "JAVA_TOOL_OPTIONS",
+        `${existingJavaToolOptions} -Djavax.net.debug=all`,
+      );
+    }
+
     // Write diagnostics to the database that we previously stored in memory because the database
     // did not exist until now.
     flushDiagnostics(config);