Security Warning Dialog timeout

[tzjan]

Hello,
during the startup of our webstart application the following dialog is raised.
Security Warning The websites's HTTPS certificate cannot be verified. Do you want to continue?
When I confirm this with the button "Yes" in less than about 20 seconds, all is going well and the application
starts up without an issue.

When I wait more than 20 seconds webstart runs in an exception:

Launch exception
netx: Launch Error: Could not launch JNLP file. ( (java.net.SocketException: Software caused connection abort: socket write error (Software caused connection abort: socket write error)))
Returning value: YES 
Setting value: YES 

It looks like an timeout, but I can't find something to change this timeout.
I have tried:

sun.net.client.defaultConnectTimeout=-1
sun.net.client.defaultReadTimeout=-1

I only found that the following Class is used to raise the dialog:
net.adoptopenjdk.icedteaweb.client.parts.dialogs.security.CertWarningPane

My question is, how can I change this behavior? Can I change the timeout?

Thank You

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OpenWebStart 1.6.0 IcedTeaWeb icedtea-web-2.0.0-alpha24
Used Java OpenJDK11U-jre_x86-32_windows_hotspot_11.0.16.1_1 on Win 10