diff --git a/rascal-lsp/src/main/checkerframework/lsp4j.astub b/rascal-lsp/src/main/checkerframework/lsp4j.astub
index ad2326e30..a1bd7470e 100644
--- a/rascal-lsp/src/main/checkerframework/lsp4j.astub
+++ b/rascal-lsp/src/main/checkerframework/lsp4j.astub
@@ -107,3 +107,347 @@ public class CallHierarchyItem {
   public void setDetail(@Nullable final String detail) { }
   public void setData(@Nullable final Object data) { }
 }
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class ClientCapabilities {
+  public @Nullable WorkspaceClientCapabilities getWorkspace() {}
+  public @Nullable TextDocumentClientCapabilities getTextDocument() {}
+  public @Nullable NotebookDocumentClientCapabilities getNotebookDocument() {}
+  public @Nullable WindowClientCapabilities getWindow() {}
+  public @Nullable GeneralClientCapabilities getGeneral() {}
+  public @Nullable Object getExperimental() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class WorkspaceClientCapabilities {
+  public @Nullable Boolean getApplyEdit() {}
+  public @Nullable WorkspaceEditCapabilities getWorkspaceEdit() {}
+  public @Nullable DidChangeConfigurationCapabilities getDidChangeConfiguration() {}
+  public @Nullable DidChangeWatchedFilesCapabilities getDidChangeWatchedFiles() {}
+  public @Nullable SymbolCapabilities getSymbol() {}
+  public @Nullable ExecuteCommandCapabilities getExecuteCommand() {}
+  public @Nullable Boolean getWorkspaceFolders() {}
+  public @Nullable Boolean getConfiguration() {}
+  public @Nullable SemanticTokensWorkspaceCapabilities getSemanticTokens() {}
+  public @Nullable CodeLensWorkspaceCapabilities getCodeLens() {}
+  public @Nullable FileOperationsWorkspaceCapabilities getFileOperations() {}
+  public @Nullable InlayHintWorkspaceCapabilities getInlayHint() {}
+  public @Nullable InlineValueWorkspaceCapabilities getInlineValue() {}
+  public @Nullable DiagnosticWorkspaceCapabilities getDiagnostics() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class TextDocumentClientCapabilities {
+  public @Nullable SynchronizationCapabilities getSynchronization() {}
+  public @Nullable CompletionCapabilities getCompletion() {}
+  public @Nullable HoverCapabilities getHover() {}
+  public @Nullable SignatureHelpCapabilities getSignatureHelp() {}
+  public @Nullable ReferencesCapabilities getReferences() {}
+  public @Nullable DocumentHighlightCapabilities getDocumentHighlight() {}
+  public @Nullable DocumentSymbolCapabilities getDocumentSymbol() {}
+  public @Nullable FormattingCapabilities getFormatting() {}
+  public @Nullable RangeFormattingCapabilities getRangeFormatting() {}
+  public @Nullable OnTypeFormattingCapabilities getOnTypeFormatting() {}
+  public @Nullable DeclarationCapabilities getDeclaration() {}
+  public @Nullable DefinitionCapabilities getDefinition() {}
+  public @Nullable TypeDefinitionCapabilities getTypeDefinition() {}
+  public @Nullable ImplementationCapabilities getImplementation() {}
+  public @Nullable CodeActionCapabilities getCodeAction() {}
+  public @Nullable CodeLensCapabilities getCodeLens() {}
+  public @Nullable DocumentLinkCapabilities getDocumentLink() {}
+  public @Nullable ColorProviderCapabilities getColorProvider() {}
+  public @Nullable RenameCapabilities getRename() {}
+  public @Nullable PublishDiagnosticsCapabilities getPublishDiagnostics() {}
+  public @Nullable FoldingRangeCapabilities getFoldingRange() {}
+  public @Nullable TypeHierarchyCapabilities getTypeHierarchy() {}
+  public @Nullable CallHierarchyCapabilities getCallHierarchy() {}
+  public @Nullable SelectionRangeCapabilities getSelectionRange() {}
+  public @Nullable SemanticTokensCapabilities getSemanticTokens() {}
+  public @Nullable MonikerCapabilities getMoniker() {}
+  public @Nullable LinkedEditingRangeCapabilities getLinkedEditingRange() {}
+  public @Nullable InlayHintCapabilities getInlayHint() {}
+  public @Nullable InlineValueCapabilities getInlineValue() {}
+  public @Nullable DiagnosticCapabilities getDiagnostic() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class WindowClientCapabilities {
+  public @Nullable Boolean getWorkDoneProgress() {}
+  public @Nullable WindowShowMessageRequestCapabilities getShowMessage() {}
+  public @Nullable ShowDocumentCapabilities getShowDocument() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class GeneralClientCapabilities {
+  public @Nullable RegularExpressionsCapabilities getRegularExpressions() {}
+  public @Nullable MarkdownCapabilities getMarkdown() {}
+  public @Nullable StaleRequestCapabilities getStaleRequestSupport() {}
+  public @Nullable List<String> getPositionEncodings() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class WorkspaceEditCapabilities {
+  public @Nullable Boolean getDocumentChanges() {}
+  public @Nullable List<String> getResourceOperations() {}
+  public @Nullable String getFailureHandling() {}
+  public @Nullable Boolean getNormalizesLineEndings() {}
+  public @Nullable WorkspaceEditChangeAnnotationSupportCapabilities getChangeAnnotationSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DynamicRegistrationCapabilities {
+  public @Nullable Boolean getDynamicRegistration() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DidChangeWatchedFilesCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getRelativePatternSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class SymbolCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable SymbolKindCapabilities getSymbolKind() {}
+  public @Nullable SymbolTagSupportCapabilities getTagSupport() {}
+  public @Nullable WorkspaceSymbolResolveSupportCapabilities getResolveSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class SemanticTokensWorkspaceCapabilities {
+  public @Nullable Boolean getRefreshSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class CodeLensWorkspaceCapabilities {
+  public @Nullable Boolean getRefreshSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class FileOperationsWorkspaceCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getDidCreate() {}
+  public @Nullable Boolean getWillCreate() {}
+  public @Nullable Boolean getDidRename() {}
+  public @Nullable Boolean getWillRename() {}
+  public @Nullable Boolean getDidDelete() {}
+  public @Nullable Boolean getWillDelete() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class InlayHintWorkspaceCapabilities {
+    public @Nullable Boolean getRefreshSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class InlineValueWorkspaceCapabilities {
+  public @Nullable Boolean getRefreshSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DiagnosticWorkspaceCapabilities {
+  public @Nullable Boolean getRefreshSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class WorkspaceEditChangeAnnotationSupportCapabilities {
+  public @Nullable Boolean getGroupsOnLabel() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class SynchronizationCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getWillSave() {}
+  public @Nullable Boolean getWillSaveWaitUntil() {}
+  public @Nullable Boolean getDidSave() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class CompletionCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable CompletionItemCapabilities getCompletionItem() {}
+  public @Nullable CompletionItemKindCapabilities getCompletionItemKind() {}
+  public @Nullable Boolean getContextSupport() {}
+  public @Nullable InsertTextMode getInsertTextMode() {}
+  public @Nullable CompletionListCapabilities getCompletionList() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class HoverCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable List<String> getContentFormat() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class SignatureHelpCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable SignatureInformationCapabilities getSignatureInformation() {}
+  public @Nullable Boolean getContextSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DocumentSymbolCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable SymbolKindCapabilities getSymbolKind() {}
+  public @Nullable Boolean getHierarchicalDocumentSymbolSupport() {}
+  public @Nullable SymbolTagSupportCapabilities getTagSupport() {}
+  public @Nullable Boolean getLabelSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DeclarationCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getLinkSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DefinitionCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getLinkSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class TypeDefinitionCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getLinkSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class ImplementationCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getLinkSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class CodeActionCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable CodeActionLiteralSupportCapabilities getCodeActionLiteralSupport() {}
+  public @Nullable Boolean getIsPreferredSupport() {}
+  public @Nullable Boolean getDisabledSupport() {}
+  public @Nullable Boolean getDataSupport() {}
+  public @Nullable CodeActionResolveSupportCapabilities getResolveSupport() {}
+  public @Nullable Boolean getHonorsChangeAnnotations() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class DocumentLinkCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getTooltipSupport() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class RenameCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getPrepareSupport() {}
+  public @Nullable PrepareSupportDefaultBehavior getPrepareSupportDefaultBehavior() {}
+  public @Nullable Boolean getHonorsChangeAnnotations() {}
+}
+
+
+package org.eclipse.lsp4j;
+
+import org.checkerframework.checker.nullness.qual.*;
+
+public class SemanticTokensCapabilities extends DynamicRegistrationCapabilities {
+  public @Nullable Boolean getOverlappingTokenSupport() {}
+  public @Nullable Boolean getMultilineTokenSupport() {}
+  public @Nullable Boolean getServerCancelSupport() {}
+  public @Nullable Boolean getAugmentsSyntaxTokens() {}
+}
diff --git a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java
index c0669dc8b..75afbb69a 100644
--- a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java
+++ b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java
@@ -47,12 +47,14 @@
 import org.eclipse.lsp4j.FileDelete;
 import org.eclipse.lsp4j.RenameFilesParams;
 import org.eclipse.lsp4j.ServerCapabilities;
+import org.eclipse.lsp4j.WorkspaceClientCapabilities;
 import org.eclipse.lsp4j.WorkspaceFolder;
 import org.eclipse.lsp4j.WorkspaceFoldersOptions;
 import org.eclipse.lsp4j.WorkspaceServerCapabilities;
 import org.eclipse.lsp4j.services.LanguageClient;
 import org.eclipse.lsp4j.services.LanguageClientAware;
 import org.eclipse.lsp4j.services.WorkspaceService;
+import org.rascalmpl.vscode.lsp.util.Nullables;
 import org.rascalmpl.vscode.lsp.util.concurrent.CompletableFutureUtils;
 import org.rascalmpl.vscode.lsp.util.locations.Locations;
 
@@ -82,14 +84,12 @@ public void initialize(ClientCapabilities clientCap, @Nullable List<WorkspaceFol
             this.workspaceFolders.addAll(currentWorkspaceFolders);
         }
 
-        var clientWorkspaceCap = clientCap.getWorkspace();
-
         if (capabilities.getWorkspace() == null) {
             capabilities.setWorkspace(new WorkspaceServerCapabilities());
         }
 
         var workspaceCapabilities = capabilities.getWorkspace();
-        if (clientWorkspaceCap != null && clientWorkspaceCap.getWorkspaceFolders().booleanValue()) {
+        if (Nullables.has(clientCap.getWorkspace(), WorkspaceClientCapabilities::getWorkspaceFolders)) {
             var folderOptions = new WorkspaceFoldersOptions();
             folderOptions.setSupported(true);
             folderOptions.setChangeNotifications(true);
diff --git a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/CompletionCapability.java b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/CompletionCapability.java
index 8a7da71ac..7ceb114e7 100644
--- a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/CompletionCapability.java
+++ b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/CompletionCapability.java
@@ -31,9 +31,12 @@
 import java.util.stream.Stream;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.eclipse.lsp4j.ClientCapabilities;
+import org.eclipse.lsp4j.CompletionCapabilities;
 import org.eclipse.lsp4j.CompletionOptions;
 import org.eclipse.lsp4j.CompletionRegistrationOptions;
 import org.eclipse.lsp4j.ServerCapabilities;
+import org.eclipse.lsp4j.TextDocumentClientCapabilities;
+import org.rascalmpl.vscode.lsp.util.Nullables;
 
 import io.usethesource.vallang.IString;
 
@@ -76,7 +79,7 @@ protected CompletionRegistrationOptions mergeOptions(CompletionRegistrationOptio
 
     @Override
     protected boolean isDynamicallySupportedBy(ClientCapabilities client) {
-        return client.getTextDocument().getCompletion().getDynamicRegistration();
+        return Nullables.has(client.getTextDocument(), TextDocumentClientCapabilities::getCompletion, CompletionCapabilities::getDynamicRegistration);
     }
 
     @Override
diff --git a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/FileOperationCapability.java b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/FileOperationCapability.java
index 1b7042849..1a6b26712 100644
--- a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/FileOperationCapability.java
+++ b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/capabilities/FileOperationCapability.java
@@ -39,8 +39,11 @@
 import org.eclipse.lsp4j.FileOperationPatternKind;
 import org.eclipse.lsp4j.FileOperationPatternOptions;
 import org.eclipse.lsp4j.FileOperationsServerCapabilities;
+import org.eclipse.lsp4j.FileOperationsWorkspaceCapabilities;
 import org.eclipse.lsp4j.ServerCapabilities;
+import org.eclipse.lsp4j.WorkspaceClientCapabilities;
 import org.eclipse.lsp4j.WorkspaceServerCapabilities;
+import org.rascalmpl.vscode.lsp.util.Nullables;
 import org.rascalmpl.vscode.lsp.util.Sets;
 import org.rascalmpl.vscode.lsp.util.concurrent.CompletableFutureUtils;
 
@@ -58,7 +61,7 @@ public abstract class FileOperationCapability extends AbstractDynamicCapability<
 
     @Override
     protected final boolean isDynamicallySupportedBy(ClientCapabilities clientCapabilities) {
-        return clientCapabilities.getWorkspace().getFileOperations().getDynamicRegistration();
+        return Nullables.has(clientCapabilities.getWorkspace(), WorkspaceClientCapabilities::getFileOperations, FileOperationsWorkspaceCapabilities::getDynamicRegistration);
     }
 
     @Override
diff --git a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalWorkspaceService.java b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalWorkspaceService.java
index e7e1e340c..5ed845023 100644
--- a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalWorkspaceService.java
+++ b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalWorkspaceService.java
@@ -34,10 +34,13 @@
 import org.eclipse.lsp4j.FileOperationOptions;
 import org.eclipse.lsp4j.FileOperationPattern;
 import org.eclipse.lsp4j.FileOperationsServerCapabilities;
+import org.eclipse.lsp4j.FileOperationsWorkspaceCapabilities;
 import org.eclipse.lsp4j.ServerCapabilities;
+import org.eclipse.lsp4j.WorkspaceClientCapabilities;
 import org.eclipse.lsp4j.WorkspaceFolder;
 import org.rascalmpl.vscode.lsp.BaseWorkspaceService;
 import org.rascalmpl.vscode.lsp.IBaseTextDocumentService;
+import org.rascalmpl.vscode.lsp.util.Nullables;
 
 public class RascalWorkspaceService extends BaseWorkspaceService {
 
@@ -52,20 +55,18 @@ public void initialize(ClientCapabilities clientCap, @Nullable List<WorkspaceFol
             ServerCapabilities capabilities) {
         super.initialize(clientCap, currentWorkspaceFolders, capabilities);
 
-        var clientCapabilities = clientCap.getWorkspace();
         if (capabilities.getWorkspace().getFileOperations() == null) {
             capabilities.getWorkspace().setFileOperations(new FileOperationsServerCapabilities());
         }
         var fileOperationCapabilities = capabilities.getWorkspace().getFileOperations();
         var whichFiles = new FileOperationOptions(fileFilters);
-        var operations = clientCapabilities.getFileOperations();
-        if (operations != null && operations.getDidCreate().booleanValue()) {
+        if (Nullables.has(clientCap.getWorkspace(), WorkspaceClientCapabilities::getFileOperations, FileOperationsWorkspaceCapabilities::getDidCreate)) {
             fileOperationCapabilities.setDidCreate(whichFiles);
         }
-        if (operations != null && operations.getDidRename().booleanValue()) {
+        if (Nullables.has(clientCap.getWorkspace(), WorkspaceClientCapabilities::getFileOperations, FileOperationsWorkspaceCapabilities::getDidRename)) {
             fileOperationCapabilities.setDidRename(whichFiles);
         }
-        if (operations != null && operations.getDidDelete().booleanValue()) {
+        if (Nullables.has(clientCap.getWorkspace(), WorkspaceClientCapabilities::getFileOperations, FileOperationsWorkspaceCapabilities::getDidDelete)) {
             fileOperationCapabilities.setDidDelete(whichFiles);
         }
     }
diff --git a/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/util/Nullables.java b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/util/Nullables.java
new file mode 100644
index 000000000..c8c2c0f5e
--- /dev/null
+++ b/rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/util/Nullables.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2018-2025, NWO-I CWI and Swat.engineering
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.rascalmpl.vscode.lsp.util;
+
+import java.util.function.Function;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+
+/**
+ * Utility class for deeply nested nullable values.
+ */
+public class Nullables {
+
+    private Nullables () { /* hide implicit constructor */}
+
+    /**
+     * Check a boolean value in a nullable object.
+     * @param <A> The type of the containing object.
+     * @param a The nullable containing object.
+     * @param hasFunc The boolean getter.
+     * @return True if the objects are non-null and the boolean is true, false otherwise.
+     */
+    public static <A> boolean has(@Nullable A a, Function<A, @Nullable Boolean> hasFunc) {
+        return get(a, hasFunc, false);
+    }
+
+    /**
+     * Check a boolean value nested in a nullable object hierarchy.
+     * @param <A> The type of the outer containing object.
+     * @param <B> The type of the inner containing object, contained in {@link A}.
+     * @param a The nullable containing object.
+     * @param getFunc The getter for the inner object.
+     * @param hasFunc The boolean getter.
+     * @return True if both objects are non-null and the boolean is true, false otherwise.
+     */
+    public static <A, B> boolean has(@Nullable A a, Function<A, @Nullable B> getFunc, Function<B, @Nullable Boolean> hasFunc) {
+        if (a == null) {
+            return false;
+        }
+        return has(getFunc.apply(a), hasFunc);
+    }
+
+    /**
+     * Get a value from a nullable object.
+     * @param <A> The type of the containing object.
+     * @param <B> The type of the value.
+     * @param a The nullable containing object.
+     * @param getFunc The value getter.
+     * @param defaultVal The value to return when either `a` or the return value of the getter is `null`.
+     * @return The gotten value if everything is non-null, `defaultVal` otherwise.
+     */
+    public static <A, B> @PolyNull B get(@Nullable A a, Function<A, @Nullable B> getFunc, @PolyNull B defaultVal) {
+        if (a == null) {
+            return defaultVal;
+        }
+        var b = getFunc.apply(a);
+        if (b == null) {
+            return defaultVal;
+        }
+        return b;
+    }
+
+    /**
+     * Get a value from a nullable object hierarchy.
+     * @param <A> The type of the outer containing object.
+     * @param <B> The type of the inner containing object.
+     * @param <C> The type of the value to get.
+     * @param a The nullable outer containing object.
+     * @param getFunc1 The inner object getter.
+     * @param getFunc2 The value getter.
+     * @param defaultVal The value to return when the outer or inner object is null, or the value is null.
+     * @return The gotten value if everything is non-null, `defaultVal` otherwise.
+     */
+    public static <A, B, C> @PolyNull C get(@Nullable A a, Function<A, @Nullable B> getFunc1, Function<B, @Nullable C> getFunc2, @PolyNull C defaultVal) {
+        return get(get(a, getFunc1, null), getFunc2, defaultVal);
+    }
+
+}