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For gadgets to work, the SSL certificate must be imported in the JVM trust store:
Because Java keytool does not accept PEM file format, you will need to convert cert-key.pem into DER format.
openssl x509 -outform der -in cert-key.pem -out cert-key.der
Import your certificate to the JVM trust store using the following command:
keytool -import -trustcacerts -file cert-key.der -keystore $JAVA_HOME/jre/lib/security/cacerts -alias proxy1.com
The default password of the JVM's trust store is "changeit".