Fix failed cast to TypeDeclaration in file paste event

[hopehadfield]

Fixes issues pasting text with implicitly declared classes into the file explorer.

[rgrunber]

Thanks. For those interested, the error :

!ENTRY org.eclipse.jdt.ls.core 4 2 2024-08-13 16:03:50.652
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jdt.ls.core".
!STACK 0
java.lang.ClassCastException: class org.eclipse.jdt.core.dom.ImplicitTypeDeclaration cannot be cast to class org.eclipse.jdt.core.dom.TypeDeclaration (org.eclipse.jdt.core.dom.ImplicitTypeDeclaration and org.eclipse.jdt.core.dom.TypeDeclaration are in unnamed module of loader org.eclipse.osgi.internal.loader.EquinoxClassLoader @644648f7)
	at org.eclipse.jdt.ls.core.internal.handlers.PasteEventHandler.handleFilePasteEvent(PasteEventHandler.java:371)
	at org.eclipse.jdt.ls.core.internal.JDTDelegateCommandHandler.executeCommand(JDTDelegateCommandHandler.java:217)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler$1.run(WorkspaceExecuteCommandHandler.java:230)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler.executeCommand(WorkspaceExecuteCommandHandler.java:220)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$4(JDTLanguageServer.java:606)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:87)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.scan(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)

from pasting something as simple as public void test () {} or anything that lacks a proper type declaration.

[rgrunber]

LGTM. I like that it only generates the Untitled file when there is "something" substantial, like an actual method declaration.