https://www.baeldung.com/java-ssl-handshake-failures

keytool -genkey -keypass password -storepass password -keystore serverkeystore.jks

What is your first and last name?
  [Unknown]:  localhost
What is the name of your organizational unit?
  [Unknown]:  pippo
What is the name of your organization?
  [Unknown]:  orgpippo
What is the name of your City or Locality?
  [Unknown]:  Zurich
What is the name of your State or Province?
  [Unknown]:  ZU
What is the two-letter country code for this unit?
  [Unknown]:  CH
Is CN=pierluigi vernetto, OU=pippo, O=orgpippo, L=Zurich, ST=ZU, C=CH correct?
  [no]:  yes

keytool -export -storepass password -file server.cer -keystore serverkeystore.jks

Certificate stored in file server.cer

keytool -import -v -trustcacerts -file server.cer -keypass password -storepass password -keystore clienttruststore.jks

keytool -genkey -keypass password -storepass password -keystore clientkeystore.jks

What is your first and last name?
  [Unknown]:  pierluigi
What is the name of your organizational unit?
  [Unknown]:  puppoou
What is the name of your organization?
  [Unknown]:  puppoo
What is the name of your City or Locality?
  [Unknown]:  zurich
What is the name of your State or Province?
  [Unknown]:  zh
What is the two-letter country code for this unit?
  [Unknown]:  ch
Is CN=pierluigi, OU=puppoou, O=puppoo, L=zurich, ST=zh, C=ch correct?
  [no]:  yes

keytool -export -storepass password -file client.cer -keystore clientkeystore.jks

keytool -import -v -trustcacerts -file client.cer -keypass password -storepass password -keystore servertruststore.jks

keytool -importkeystore -srckeystore clientkeystore.jks -destkeystore clientkeystore.p12 -deststoretype PKCS12 -srcalias mykey -deststorepass password -destkeypass password openssl pkcs12 -in clientkeystore.p12 -nokeys -out clientkey.pem

openssl s_client -connect localhost:443 -CAfile cacert.pem -cert clientcert.pem -key clientkey.pem -state -tls1_2