Adding new cacert entry into AdoptOpenJDK

I downloaded latest Tomcat source and it failed to get the dependencies.

      cd src/github/tomcat
      ant download-test-compile
            [get] Error getting https://repo.maven.apache.org/maven2/junit/junit/4.12/junit-4.12.jar to C:\Users\zemian\tomcat-build-libs\download-2000731528.tmp

    BUILD FAILED
    C:\Users\zemian\src\github\tomcat\build.xml:2705: The following error occurred while executing this line:
    C:\Users\zemian\src\github\tomcat\build.xml:3051: javax.net.ssl.SSLException: java.lang.RuntimeException: Unexpected error: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty
            at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)

It turns out this error is caused by the OpenJDK 8 that I am using. The one I got is from https://adoptopenjdk.net/, and the $JAVA_HOME/jre/lib/security/cacert file has no entries for trusted CA certs!

So I found few solutions:

1. Find a copy of OracleJDK and copy their cacerts over.

2. If you are on Linux, you can try installing cacerts using tools the OS provided. (eg: Ubuntu can be done like here: https://stackoverflow.com/questions/6784463/error-trustanchors-parameter-must-be-non-empty)

3. Upgrade OpenJDK to 10

4. Or the quick way, go to the site that gives you problem, export their cert using the browser, and then import into to the cacerts file.

So for me, I went to https://repo.maven.apache.org/ and exported repomavenapacheorg.crt, and then I ran the following:

cd $JAVA_HOME/jre/lib/security
keytool -keystore cacerts -storepasswd changeit -importcert -file 'Downloads/repomavenapacheorg.crt' -trustcacerts
keytool -keystore cacerts -storepasswd changeit -list

This fixed my problem.