duplicated quickfixes while editing Java source

[martinlippert]

In Eclipse, using the latest nightly snapshot build, having a petclinic project in the workspace.
I have OwnerController open in an editor. There are a few validations for Unnecessary Path Variable Definition showing up. Pressing Cmd-1 shows up three quick fixes Remove Implicit Web Annotation Name. Al that looks correct.

Now, I am editing the file and sometimes (not always) the quick fixes get duplicated in the quick fix popup after pressing Cmd-1. It looks like when saving the file, the quick fix popup looks good again, but editing the file seems to sometimes cause a duplication. Especially doing Undo operations seems to trigger the duplication.

[BoykoAlex]

This is in 4.35 as well but I cannot reproduce this with the dev environment... at least yet

[BoykoAlex]

Happens for 2 reasons.

1. Boot LS sends the same publish diagnostics message twice in quick succession
2. LSP4E marker update mechanics schedules jobs to update markers but jobs run in parallel and hence some markers are added twice.

I have fixed the 1. with b5446a1
The second part is for lsp4e. We either need to create a scheduling rule to update lsp4e markers as currently this rule is null or run the job's body in a synchronized block.