I've changed the next version to create keystores that expire after 20,000 days instead of the current 10,000 days. For now you can build it in the command line by using
keytool -genkey -keystore keystore_filename -alias mykeystore -keyalg RSA -keysize 2048 -validity 20000
-storepass mypassword -keypass mypasswordagain -dname "CN=fullname, O=companyname, L=city, C=country"
where
keystore_filename is the file to create,
mypassword and
mypasswordagain are the password you want to use, and the fields at the end are your details, which can be left blank if desired, for example