in src/main/java/org/apache/maven/resolver/internal/ant/types/Dependencies.java [55:85]
public void validate( Task task )
{
if ( isReference() )
{
getRef().validate( task );
}
else
{
if ( getPom() != null && getPom().getFile() == null )
{
throw new BuildException( "A <pom> used for dependency resolution has to be backed by a pom.xml file" );
}
Map<String, String> ids = new HashMap<String, String>();
for ( DependencyContainer container : containers )
{
container.validate( task );
if ( container instanceof Dependency )
{
Dependency dependency = (Dependency) container;
String id = dependency.getVersionlessKey();
String collision = ids.put( id, dependency.getVersion() );
if ( collision != null )
{
throw new BuildException( "You must not declare multiple <dependency> elements"
+ " with the same coordinates but got " + id + " -> " + collision + " vs "
+ dependency.getVersion() );
}
}
}
}
}