Error executing JNLP file (translucency is not supported.)

I need to run this .jnlp file because some bureaucracy in my home country is still stuck in the 90s. I need to execute this to comply with some legal requirement.

I’ve made some research and usually this problem should be solved by installing jre8-openjdk. So I installed it.

I also ran:

sudo archlinux-java set java-8-openjdk/jre

If I run java -version I get:

Picked up _JAVA_OPTIONS:  -Djavax.net.ssl.trustStore=/etc/ssl/certs/java/cacerts
openjdk version "1.8.0_292"
OpenJDK Runtime Environment (build 1.8.0_292-b10)
OpenJDK 64-Bit Server VM (build 25.292-b10, mixed mode)

If I run javaws, I get:

selected jre: /usr/lib/jvm/java-8-openjdk/jre
Warning!, Fall back in resolve_jar to hardcoded paths: 
/usr/share/java/js.jar
Picked up _JAVA_OPTIONS:  -Djavax.net.ssl.trustStore=/etc/ssl/certs/java/cacerts
Unable to use Firefox's proxy settings. Using "DIRECT" as proxy type.

Still, if I try to execute the .jnlp file like javaws ./Emissor.jnlp, I get an error:

netx: Launch Error: Could not launch JNLP file. ( ( (TRANSLUCENT translucency is not supported.)))
net.sourceforge.jnlp.LaunchException: Fatal: Launch Error: Could not launch JNLP file. The application has not been initialized, for more information execute javaws/browser from the command line and send a bug report.
	at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:583)
	at net.sourceforge.jnlp.Launcher$TgThread.run(Launcher.java:946)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:577)
	... 1 more
Caused by: java.lang.ExceptionInInitializerError
	at br.com.soluti.baixadecertificados.run.InstallCertificado.main(Unknown Source)
	... 6 more
Caused by: java.lang.UnsupportedOperationException: TRANSLUCENT translucency is not supported.
	at java.awt.Window.setOpacity(Window.java:3627)
	at java.awt.Frame.setOpacity(Frame.java:962)
	at br.com.soluti.baixadecertificados.view.v.<init>(Unknown Source)
	at br.com.soluti.baixadecertificados.view.ViewInstallCertificado.<clinit>(Unknown Source)
	... 7 more

This is the root cause apparently:

Caused by: java.lang.UnsupportedOperationException: TRANSLUCENT translucency is not supported.

Is there a way to disable this? Or to simply make it work?