Update process should check version and not allow reversion through update

[parsharma]

Issue: #759

[TomasHofman]

Relevant wildfly-channel issue that I think we would need implemented there in order to complete this functionality:
wildfly-extras/wildfly-channel#292

[TomasHofman]

A good next step could be to obtain a list of manifests used by the current installation. I think it should be possible to obtain maven GAVs (or URLs) of the current manifests. If there are any Maven based manifest found in the list, they should be matched against the list of new manifests (which the user want to upgrade to) used by the ChannelSession.

(That list of new manifests is currently simulated by the findManifestUpdates() method, hard-coded to only return org.jbosss.eap.channels:eap-8.0 manifest artifact, because we don't know how to obtain these data.)

[parsharma]

Hello @TomasHofman,
I have updated the code where we are getting list of manifests from the current installation.

[TomasHofman]

Now can we get the list of manifests currently used by the installation? Maybe from the InstallationMetadata class?

If we can have that, we can try to obtain an intersection from those two lists (manifests groupId:artifactId s that are present in both currently installed manifest and the newly available manifests used by the channelSession).

Once we have that intersection, we can try to compare the versions to see if they are upgrading or downgrading.