[CQ] InspectorView de-duping and null-awareness (#8173)

Some opportunistic `InspectorView` clean-up.

* a bit of de-duplication and
* some added null-awareness

---

- [x] I’ve reviewed the contributor guide and applied the relevant
portions to this PR.

<details>
  <summary>Contribution guidelines:</summary><br>

- See our [contributor
guide]([https://github.com/dart-lang/sdk/blob/main/CONTRIBUTING.md](https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview)
for general expectations for PRs.
- Larger or significant changes should be discussed in an issue before
creating a PR.
- Dart contributions to our repos should follow the [Dart style
guide](https://dart.dev/guides/language/effective-dart) and use `dart
format`.
- Java and Kotlin contributions should strive to follow Java and Kotlin
best practices
([discussion](#8098)).
</details>

Author: pq

flutter-idea/src/io/flutter/devtools/DevToolsUrl.java

@@ -9,6 +9,7 @@
 import io.flutter.sdk.FlutterSdkUtil;
 import io.flutter.sdk.FlutterSdkVersion;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
@@ -37,27 +38,28 @@ public class DevToolsUrl {
   @NotNull private final DevToolsUtils devToolsUtils;
 
   public static class Builder {
-    private String devToolsHost;
+    private @Nullable String devToolsHost;
 
     private int devToolsPort;
-    private String vmServiceUri;
+    private @Nullable String vmServiceUri;
     private String page;
     private Boolean embed;
     private String widgetId;
     private String hide;
 
-    private FlutterSdkVersion flutterSdkVersion;
+    private @Nullable FlutterSdkVersion flutterSdkVersion;
     private WorkspaceCache workspaceCache;
     private DevToolsIdeFeature ideFeature;
 
     private DevToolsUtils devToolsUtils;
 
     private FlutterSdkUtil flutterSdkUtil;
 
-    public Builder() {}
+    public Builder() {
+    }
 
     @NotNull
-    public Builder setDevToolsHost(String devToolsHost) {
+    public Builder setDevToolsHost(@Nullable String devToolsHost) {
       this.devToolsHost = devToolsHost;
       return this;
     }
@@ -69,7 +71,7 @@ public Builder setDevToolsPort(int devToolsPort) {
     }
 
     @NotNull
-    public Builder setVmServiceUri(String vmServiceUri) {
+    public Builder setVmServiceUri(@Nullable String vmServiceUri) {
       this.vmServiceUri = vmServiceUri;
       return this;
     }
@@ -105,7 +107,7 @@ public Builder setDevToolsUtils(DevToolsUtils devToolsUtils) {
     }
 
     @NotNull
-    public Builder setFlutterSdkVersion(FlutterSdkVersion sdkVersion) {
+    public Builder setFlutterSdkVersion(@Nullable FlutterSdkVersion sdkVersion) {
       this.flutterSdkVersion = sdkVersion;
       return this;
     }
@@ -163,10 +165,12 @@ private DevToolsUrl(Builder builder) {
     if (builder.workspaceCache != null && builder.workspaceCache.isBazel()) {
       this.canUseDevToolsPathUrl = true;
       this.canUseMultiEmbed = true;
-    } else if (flutterSdkVersion != null) {
+    }
+    else if (flutterSdkVersion != null) {
       this.canUseDevToolsPathUrl = flutterSdkVersion.canUseDevToolsPathUrls();
       this.canUseMultiEmbed = flutterSdkVersion.canUseDevToolsMultiEmbed();
-    } else {
+    }
+    else {
       this.canUseDevToolsPathUrl = false;
       this.canUseMultiEmbed = false;
     }
@@ -192,12 +196,14 @@ public String getUrlString() {
       if (!this.canUseMultiEmbed) {
         // This is for older versions of DevTools that do not support embed= one vs. many.
         params.add("embed=true");
-      } else {
+      }
+      else {
         if (hide != null) {
           // If we are using the hide param, we can assume that we are trying to embed multiple tabs.
           params.add("embedMode=many");
           params.add("hide=" + hide);
-        } else {
+        }
+        else {
           params.add("embedMode=one");
         }
       }

flutter-idea/src/io/flutter/jxbrowser/InstallationFailedReason.java

@@ -1,15 +1,18 @@
 package io.flutter.jxbrowser;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 public class InstallationFailedReason {
-    public FailureType failureType;
-    public String detail;
+  public final @NotNull FailureType failureType;
+  public final @Nullable String detail;
 
-    public InstallationFailedReason(FailureType failureType) {
-        this(failureType, null);
-    }
+  public InstallationFailedReason(@NotNull FailureType failureType) {
+    this(failureType, null);
+  }
 
-    InstallationFailedReason(FailureType failureType, String detail) {
-        this.failureType = failureType;
-        this.detail = detail;
-    }
+  InstallationFailedReason(@NotNull FailureType failureType, @Nullable String detail) {
+    this.failureType = failureType;
+    this.detail = detail;
+  }
 }

flutter-idea/src/io/flutter/settings/FlutterSettings.java

@@ -11,6 +11,7 @@
 import com.intellij.openapi.util.registry.Registry;
 import com.intellij.util.EventDispatcher;
 import com.jetbrains.lang.dart.analyzer.DartClosingLabelManager;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.EventListener;
 import java.util.Objects;
@@ -59,12 +60,12 @@ public static void setInstance(FlutterSettings instance) {
     testInstance = instance;
   }
 
-  public static FlutterSettings getInstance() {
+  public static @NotNull FlutterSettings getInstance() {
     if (testInstance != null) {
       return testInstance;
     }
 
-    return Objects.requireNonNull(ApplicationManager.getApplication()).getService(FlutterSettings.class);
+    return Objects.requireNonNull(Objects.requireNonNull(ApplicationManager.getApplication()).getService(FlutterSettings.class));
   }
 
   protected static PropertiesComponent getPropertiesComponent() {

flutter-idea/src/io/flutter/utils/OpenApiUtils.java

@@ -38,6 +38,12 @@ public class OpenApiUtils {
     return modules == null ? Module.EMPTY_ARRAY : modules;
   }
 
+  public static void safeExecuteOnPooledThread(@NotNull Runnable action) {
+    var application = ApplicationManager.getApplication();
+    if (application == null) return;
+    application.executeOnPooledThread(action);
+  }
+
   public static void safeRunReadAction(@NotNull Runnable runnable) {
     Application application = ApplicationManager.getApplication();
     if (application == null) return;

flutter-idea/src/io/flutter/view/InspectorView.java

@@ -8,7 +8,6 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.intellij.ide.browsers.BrowserLauncher;
 import com.intellij.openapi.Disposable;
-import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.components.Storage;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.progress.EmptyProgressIndicator;
@@ -84,8 +83,8 @@ public class InspectorView implements Disposable {
 
   private InspectorViewToolWindowManagerListener toolWindowListener;
   private int devToolsInstallCount = 0;
-  private final JxBrowserUtils jxBrowserUtils;
-  private final JxBrowserManager jxBrowserManager;
+  private final @NotNull JxBrowserUtils jxBrowserUtils;
+  private final @NotNull JxBrowserManager jxBrowserManager;
 
   public InspectorView(@NotNull Project project) {
     this(project, JxBrowserManager.getInstance(), new JxBrowserUtils(), new ViewUtils());
@@ -95,7 +94,7 @@ public InspectorView(@NotNull Project project) {
   @NonInjectable
   protected InspectorView(@NotNull Project project,
                           @NotNull JxBrowserManager jxBrowserManager,
-                          JxBrowserUtils jxBrowserUtils,
+                          @NotNull JxBrowserUtils jxBrowserUtils,
                           ViewUtils viewUtils) {
     myProject = project;
     this.jxBrowserUtils = jxBrowserUtils;
@@ -119,11 +118,11 @@ void initToolWindow(@NotNull ToolWindow window) {
     updateForEmptyContent(window);
   }
 
-  private void addBrowserInspectorViewContent(FlutterApp app,
-                                              ToolWindow toolWindow,
+  private void addBrowserInspectorViewContent(@NotNull FlutterApp app,
+                                              @NotNull ToolWindow toolWindow,
                                               boolean isEmbedded,
                                               DevToolsIdeFeature ideFeature,
-                                              DevToolsInstance devToolsInstance) {
+                                              @NotNull DevToolsInstance devToolsInstance) {
     assert (SwingUtilities.isEventDispatchThread());
 
     final ContentManager contentManager = toolWindow.getContentManager();
@@ -199,7 +198,7 @@ private void addBrowserInspectorViewContent(FlutterApp app,
     }
   }
 
-  private Optional<EmbeddedBrowser> embeddedBrowserOptional() {
+  private @NotNull Optional<EmbeddedBrowser> embeddedBrowserOptional() {
     if (myProject.isDisposed()) {
       return Optional.empty();
     }
@@ -264,6 +263,10 @@ private void openInspectorWithDevTools(FlutterApp app,
                                          boolean isEmbedded,
                                          DevToolsIdeFeature ideFeature,
                                          boolean forceDevToolsRestart) {
+    if (toolWindow == null) {
+      LOG.error("Unable to open Inspector with DevTools: toolwindow is null");
+      return;
+    }
     AsyncUtils.whenCompleteUiThread(
       forceDevToolsRestart
       ? DevToolsService.getInstance(myProject).getDevToolsInstanceWithForcedRestart()
@@ -281,7 +284,7 @@ private void openInspectorWithDevTools(FlutterApp app,
           return;
         }
 
-        if (instance == null) {
+        if (instance == null || app == null) {
           viewUtils.presentLabel(toolWindow, DEVTOOLS_FAILED_LABEL);
           return;
         }
@@ -311,7 +314,7 @@ protected void handleJxBrowserInstallationInProgress(FlutterApp app, ToolWindow
 
   protected void startJxBrowserInstallationWaitingThread(FlutterApp app, ToolWindow toolWindow,
                                                          DevToolsIdeFeature ideFeature) {
-    ApplicationManager.getApplication().executeOnPooledThread(() -> {
+    OpenApiUtils.safeExecuteOnPooledThread(() -> {
       waitForJxBrowserInstallation(app, toolWindow, ideFeature);
     });
   }
@@ -393,21 +396,6 @@ protected void presentOpenDevToolsOptionWithMessage(FlutterApp app,
     viewUtils.presentClickableLabel(toolWindow, inputs);
   }
 
-  private void replacePanelLabel(ToolWindow toolWindow, JComponent label) {
-    OpenApiUtils.safeInvokeLater(() -> {
-      final ContentManager contentManager = toolWindow.getContentManager();
-      if (contentManager.isDisposed()) {
-        return;
-      }
-
-      final JPanel panel = new JPanel(new BorderLayout());
-      panel.add(label, BorderLayout.CENTER);
-      final Content content = contentManager.getFactory().createContent(panel, null, false);
-      contentManager.removeAllContents(true);
-      contentManager.addContent(content);
-    });
-  }
-
   private void debugActiveHelper(@NotNull FlutterApp app) {
     final ToolWindowManager toolWindowManager = ToolWindowManager.getInstance(myProject);
     if (!(toolWindowManager instanceof ToolWindowManagerEx)) {
@@ -478,7 +466,7 @@ else if (jxBrowserStatus.equals(JxBrowserStatus.NOT_INSTALLED) || jxBrowserStatu
     }
   }
 
-  private void updateForEmptyContent(ToolWindow toolWindow) {
+  private void updateForEmptyContent(@NotNull ToolWindow toolWindow) {
     // There's a possible race here where the tool window gets disposed while we're displaying contents.
     if (toolWindow.isDisposed()) {
       return;
@@ -495,7 +483,7 @@ private void updateForEmptyContent(ToolWindow toolWindow) {
   }
 
   // Returns true if the toolWindow was initially closed but opened automatically on app launch.
-  private DevToolsIdeFeature updateToolWindowVisibility(ToolWindow flutterToolWindow) {
+  private @Nullable DevToolsIdeFeature updateToolWindowVisibility(@NotNull ToolWindow flutterToolWindow) {
     if (flutterToolWindow.isVisible()) {
       return DevToolsIdeFeature.TOOL_WINDOW_RELOAD;
     }

flutter-idea/src/io/flutter/view/ViewUtils.java

@@ -54,7 +54,6 @@ public void presentLabels(@NotNull ToolWindow toolWindow, @NotNull List<String>
   }
 
 
-
   public void presentClickableLabel(ToolWindow toolWindow, List<LabelInput> labels) {
     final JPanel panel = new JPanel(new GridLayout(0, 1));
 
@@ -79,7 +78,7 @@ public void presentClickableLabel(ToolWindow toolWindow, List<LabelInput> labels
     replacePanelLabel(toolWindow, center);
   }
 
-  private void replacePanelLabel(ToolWindow toolWindow, JComponent label) {
+  public void replacePanelLabel(ToolWindow toolWindow, JComponent label) {
     OpenApiUtils.safeInvokeLater(() -> {
       final ContentManager contentManager = toolWindow.getContentManager();
       if (contentManager.isDisposed()) {