Language server reports OOM for Java heap space while switching local git branch

Use VS Code to develop eclipse.jdt.ls itself, and switch local branch to a remote PR branch, language server reports OOM exception.

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:12.066
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.core 4 4 2022-07-19 13:28:25.648
!MESSAGE Background Indexer Crash Recovery
!STACK 0
java.lang.OutOfMemoryError: Java heap space
	at org.eclipse.jdt.internal.compiler.util.HashtableOfObject.<init>(HashtableOfObject.java:56)
	at org.eclipse.jdt.internal.compiler.util.HashtableOfObject.rehash(HashtableOfObject.java:184)
	at org.eclipse.jdt.internal.compiler.util.HashtableOfObject.putUnsafely(HashtableOfObject.java:157)
	at org.eclipse.jdt.internal.core.index.DiskIndex.copyQueryResults(DiskIndex.java:383)
	at org.eclipse.jdt.internal.core.index.DiskIndex.mergeWith(DiskIndex.java:570)
	at org.eclipse.jdt.internal.core.index.Index.save(Index.java:230)
	at org.eclipse.jdt.internal.core.search.indexing.IndexManager.saveIndex(IndexManager.java:1150)
	at org.eclipse.jdt.internal.core.search.indexing.AddJrtToIndex.execute(AddJrtToIndex.java:274)
	at org.eclipse.jdt.internal.core.search.processing.JobManager.run(JobManager.java:445)
	at java.base/java.lang.Thread.run(Unknown Source)

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:30.506
!MESSAGE >> workspace/executeCommand vscode.java.test.findTestTypesAndMethods

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:30.508
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.420
!MESSAGE >> workspace/executeCommand vscode.java.test.findTestTypesAndMethods

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.423
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.652
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.945
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.964
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:33.997
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.145
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.269
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.339
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.444
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.592
!MESSAGE >> workspace/executeCommand vscode.java.test.findTestTypesAndMethods

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.596
!MESSAGE >> workspace/didChangeWatchedFiles 

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.664
!MESSAGE >> workspace/executeCommand vscode.java.test.findTestTypesAndMethods

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.665
!MESSAGE >> document/codeAction

!ENTRY org.eclipse.jdt.ls.core 1 0 2022-07-19 13:28:34.668
!MESSAGE >> document/codeAction

Reproduce the problem in VS Code by switching the local branch to a remote PR branch, then inspect the workspace/didChangeWatchedFiles activity and the reported JDT indexing stack trace through DiskIndex, Index, and AddJrtToIndex. Done means the branch switch no longer causes the Java heap space failure; the issue names no test or source file to run or edit.