Gson library upgraded to 2.8.9, LSP upgraded to 3.16

[dbalek]

Upgrading Gson library to the last stable version 2.8.9.
Upgrading LSP to the last stable version 3.16.

[dbalek]

Do not merge this PR now. The following exception is thrown when starting IDE with the updated Gson library.

SEVERE [org.netbeans.modules.netbinox]: framework event com.google.gson type 2
org.osgi.framework.BundleException: The bundle "com.google.gson_2.8.8 [111]" could not be resolved. Reason: Missing Constraint: Import-Package: sun.misc; version="0.0.0"
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1332)
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1316)
	at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:323)
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:390)
	at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1184)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:559)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:544)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:457)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)
	at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.internalStart(EquinoxLauncher.java:271)
	at org.eclipse.osgi.framework.internal.core.EquinoxLauncher$2.run(EquinoxLauncher.java:246)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.start(EquinoxLauncher.java:244)
	at org.eclipse.osgi.launch.Equinox.start(Equinox.java:258)
	at org.netbeans.core.netigso.Netigso.start(Netigso.java:184)
	at org.netbeans.NetigsoHandle.startFramework(NetigsoHandle.java:188)
	at org.netbeans.ModuleManager.enable(ModuleManager.java:1458)
	at org.netbeans.ModuleManager.enable(ModuleManager.java:1254)
	at org.netbeans.core.startup.ModuleList.installNew(ModuleList.java:315)
	at org.netbeans.core.startup.ModuleList.trigger(ModuleList.java:251)
	at org.netbeans.core.startup.ModuleSystem.restore(ModuleSystem.java:298)
	at org.netbeans.core.startup.Main.getModuleSystem(Main.java:156)
	at org.netbeans.core.startup.Main.getModuleSystem(Main.java:125)
	at org.netbeans.core.startup.Main.start(Main.java:282)
	at org.netbeans.core.startup.TopThreadGroup.run(TopThreadGroup.java:98)```

[neilcsmith-net]

Removed the milestone given the do not merge label. Add back a milestone if/when this is ready.

[JaroslavTulach]

The problem has been reported to GSON guys as google/gson#1981
The proposed fix is available as google/gson#1993