[jira] [Created] (MENFORCER-335) Documentation suggests unreliable practice for dependency convergence

["Roland (JIRA)" <ji...@apache.org>]

Roland created MENFORCER-335:
--------------------------------

             Summary: Documentation suggests unreliable practice for dependency convergence
                 Key: MENFORCER-335
                 URL: https://issues.apache.org/jira/browse/MENFORCER-335
             Project: Maven Enforcer Plugin
          Issue Type: Bug
          Components: Documentation
            Reporter: Roland


The [documentation for Dependency Convergence|https://maven.apache.org/enforcer/enforcer-rules/dependencyConvergence.html] describes how to suppress an error reported by the check. This description leads to unreliable project configurations.

In the example from the documentation, using an exclusion element works for the very moment, but as soon as the dependency slf4j-jdk14 is no longer needed, the project will break since slf4j-api is still required by slf4j-nop, but not included anymore.

A more reliable and sustainable solution would be to have declarations like the following:
 * If one dependency chain ends in org.slf4j:slf4j-api:1.6.1 and another ends in org.slf4j:slf4j-api:1.6.0, use version 1.6.1.

The general pattern is:
 * If one dependency chain ends in $coordinate1 and another ends in $coordinate2, use version $version.

Using this pattern instead of globally saying "don't use version 1.6.0" would not break the above scenario where slf4j-jdk14 is no longer needed. Even better, since during dependency resolution this particular conflict does not occur anymore, this rule can be flagged as being no longer necessary.

It should be possible to specify not only the last coordinate of a dependency chain but any elements, as in the following example:
 * If one dependency chain ends in org.slf4j:slf4j-jdk14:1.6.1, org.slf4j:slf4j-api:1.6.1 and another ends in org.slf4j:slf4j-nop:1.6.0, org.slf4j:slf4j-api:1.6.0, use version 1.6.1.

As it is now, the dependency convergence test encourages Maven users to specify overly general and therefore wrong exclusion rules. This should be avoided.



--
This message was sent by Atlassian JIRA
(v7.6.14#76016)