Allow plugin dependencies to be excluded

Let me add a few words of my own.

Jetty's POM file declares "slf4j-simple" as a dependency. However,
some users of Jetty would like to override this dependency, for
example with "slf4j-log4j12".

Is this possible with Maven?

Another use case is where you define a parent pom using the maven-eclipse-plugin enabling WTP capabilities by default:

<plugin>
            	<groupId>org.apache.maven.plugins</groupId>
            	<artifactId>maven-eclipse-plugin</artifactId>
            	<configuration>
			<wtpmanifest>true</wtpmanifest>
			<wtpapplicationxml>true</wtpapplicationxml>
			<wtpversion>2.0</wtpversion>
            	</configuration>
</plugin>

Then in a child pom of a project you want to disable the WTP because you are using m2eclipse. If you do not disable/exclude the maven-eclipse-plugin you get a nasty error message in eclipse:

"An internal error occurred during: "Importing Maven projects".
loader constraint violation: when resolving method
"org.codehaus.plexus.util.xml.Xpp3DomWriter.write(Lorg/codehaus/plexus/util/xml/XMLWriter;Lorg/codehaus/plexus/util/xml/Xpp3Dom;)V"
the class loader (instance of
org/codehaus/plexus/classworlds/realm/ClassRealm) of the current
class, org/apache/maven/plugin/eclipse/writers/wtp/EclipseWtpApplicationXMLWriter,
and the class loader (instance of
org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader) for resolved
class, org/codehaus/plexus/util/xml/Xpp3DomWriter, have different
Class objects for the type org/codehaus/plexus/util/xml/XMLWriter used
in the signature"

I have jetty plugin and need to exclude jaas-1.0.jar from its dependencies.
Need something like this:
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.1.10</version>
<exclusions>
<exclusion>
<artifactId>jaas</artifactId>
<groupId>jaas</groupId>
</exclusion>
</exclusions>
</plugin>

I use IBM java, and java have this jar too, and i need use this jar only from JDK, not from jetty plugin.
Now i have conflict.

I'd put it that way: it should be possible to define the plugins classpath using the same concepts as the dependencies classpath. Which includes "exclusions"