Document the type of keystore expected

[lbruun]

For the Maven goal nbm:nbm we need to document the type of keystore expected.

I'm actually not sure what the answer, but I would assume it would be JKS. The reason why it is important to document this is because the JDK is head-over-heals on its way away from JKS in favor of PKCS#12. Or at least, that is my impression.

Today JKS is a legacy format which there is no need for anymore in the JDK. As of Java 9, PKCS#12 is the default keystore format. From what I understand, the JDK's support for the PKCS#12 caught up with that of JKS in Java 8 meaning from this version onwards the JKS format no longer had any edge over PKCS#12 format, feature wise. Hence, JKS is today redundant.

For now, this ticket is solely about documenting what it expected by the nbm-maven-plugin, not to implement support for something else than JKS.

[lbruun]

Hold on with this one. I understand the JDK as of v9 has a some kind of woodoo mechanism to detect if a keystore file is of type JKS or PKCS#12. Which may mean that the plugin actually already now supports both? Needs further qualification.