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fix: solve JDT Null Analysis Mismatch Error #1429

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Merged
rubenporras merged 1 commit into from
Nov 27, 2025
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fix: solve JDT Null Analysis Mismatch Error #1429

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7 changes: 4 additions & 3 deletions org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/symbols/LSPSymbolInWorkspaceDialog.java
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
package org.eclipse.lsp4e.operations.symbols;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
Expand Down Expand Up @@ -230,10 +231,10 @@ private static List<WorkspaceSymbol> toWorkspaceSymbols(@Nullable List<? extends
return res;
}

static List<? extends WorkspaceSymbol> eitherToWorkspaceSymbols(
static List<@Nullable ? extends WorkspaceSymbol> eitherToWorkspaceSymbols(
final @Nullable Either<List<? extends SymbolInformation>, List<@Nullable ? extends WorkspaceSymbol>> source) {
return source == null //
? List.of()
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@sebthom sebthom Nov 26, 2025

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Does List.of not work?

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@rubenporras rubenporras Nov 26, 2025

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Not for me, then I get the marker:

Null type mismatch (type annotations): required '@nonnull List<@nullable ? extends WorkspaceSymbol>' but this expression has type '@nonnull List<@nonnull WorkspaceSymbol>'

It looks to me that the JDT does not like than one is List.of() is guaranteed to be not null, and the other expression is Nullable.

I tried NullSafetyHelper.castNullable(List.of()) which also causes the JDT to complain.

It looks to me like a litimation of the JDT null analysis, or at least I do not understand why it is complaining.

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@sebthom sebthom Nov 26, 2025

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I'll check if this can be solved via a change to the external null annotations

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@sebthom sebthom Nov 26, 2025 •
edited
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@rubenporras List.of has the contract that it only returns lists with non-null elements. But you can replace List.of with Collections.emptyList() and it should work.

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@rubenporras rubenporras Nov 27, 2025

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Is this because of the external null annotations? The signature in java looks equal to me

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@sebthom sebthom Nov 27, 2025

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Yes the EEAs make the actual contract of List.of visible.

: source.map(LSPSymbolInWorkspaceDialog::toWorkspaceSymbols, Function.identity());
? Collections.emptyList()
: source.map(LSPSymbolInWorkspaceDialog::toWorkspaceSymbols, Function.identity());
}
}
3 changes: 2 additions & 1 deletion ...e.lsp4e/src/org/eclipse/lsp4e/operations/symbols/WorkspaceSymbolsQuickAccessProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
Expand Down Expand Up @@ -69,7 +70,7 @@ public QuickAccessElement[] computeElements(String query, IProgressMonitor monit
CompletableFuture.allOf(usedLanguageServerWrappers.stream()
.map(w -> w.execute(ls -> ls.getWorkspaceService().symbol(params).thenAcceptAsync((@Nullable Either<List<? extends SymbolInformation>, List<@Nullable ? extends WorkspaceSymbol>> symbols) -> {
if (symbols != null) {
res.addAll(LSPSymbolInWorkspaceDialog.eitherToWorkspaceSymbols(symbols).stream().map(WorkspaceSymbolQuickAccessElement::new)
res.addAll(LSPSymbolInWorkspaceDialog.eitherToWorkspaceSymbols(symbols).stream().filter(Objects::nonNull).map(WorkspaceSymbolQuickAccessElement::new)
.toList());
}
}))).toArray(CompletableFuture[]::new)).get(1, TimeUnit.SECONDS);
Expand Down
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