AnnotateAssistTest1d5.testAnnotateRemove failed in I-build

See: https://download.eclipse.org/eclipse/downloads/drops4/I20260904-2300/testresults/html/org.eclipse.jdt.ui.tests_ep442I-unit-linux-x86_64-java26_linux.gtk.x86_64_26.html

```
cu=[Working copy] MyMap.class [in pack.age [in lib.jar [in TestSetupProject]]] package pack.age interface MyMap V get(K) source=null

java.lang.AssertionError: cu=[Working copy] MyMap.class [in pack.age [in lib.jar [in TestSetupProject]]]
package pack.age
interface MyMap
V get(K) source=null
at org.junit.Assert.fail(Assert.java:89)
at org.junit.Assert.assertTrue(Assert.java:42)
at org.junit.Assert.assertNotNull(Assert.java:713)
at org.eclipse.jdt.ui.tests.quickfix.AbstractAnnotateAssistTests.collectAnnotateProposals(AbstractAnnotateAssistTests.java:123)
at org.eclipse.jdt.ui.tests.quickfix.AnnotateAssistTest1d5.testAnnotateRemove(AnnotateAssistTest1d5.java:260)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
```

Nothing useful in the workspace log: https://download.eclipse.org/eclipse/downloads/drops4/I20260904-2300/testresults/ep442I-unit-linux-x86_64-java26_linux.gtk.x86_64_26/org.eclipse.jdt.ui.tests.AutomatedSuite.txt

```
!ENTRY org.eclipse.jdt.ui.tests 1 0 2026-09-05 02:18:13.619
!MESSAGE testAnnotateRemove STARTING

!ENTRY org.eclipse.jdt.ui.tests 1 0 2026-09-05 02:18:13.822
!MESSAGE testAnnotateRemove DONE: FAILED
```

Start with AnnotateAssistTest1d5.java at testAnnotateRemove and AbstractAnnotateAssistTests.java at collectAnnotateProposals. Reproduce against the linked I-build test results and inspect why the MyMap.class working copy produces no annotation proposal. Done means the test reliably collects the expected proposals without the assertion failure.

Written by the indexing model from the issue text.