src/main/java/org/codehaus/mojo/exec/ExecMojo.java
private String computeClasspathString( AbstractPath specifiedClasspath )
    {
        List<String> resultList = computePath( specifiedClasspath );
        StringBuffer theClasspath = new StringBuffer();

        for ( String str : resultList )
        {
            addToClasspath( theClasspath, str );
        }

        return theClasspath.toString();
    }
private String computeClasspathString( AbstractPath specifiedClasspath )
    {
        List<String> resultList = computePath( specifiedClasspath );
        StringBuffer theClasspath = new StringBuffer();

        for ( String str : resultList )
        {
            addToClasspath( theClasspath, str );
        }

        return theClasspath.toString();
    }
Compute the classpath from the specified Classpath. The computed classpath is based on the classpathScope. The
plugin cannot know from maven the phase it is executed in. So we have to depend on the user to tell us he wants
the scope in which the plugin is expected to be executed.

@param specifiedClasspath Non null when the user restricted the dependencies, <code>null</code> otherwise (the
default classpath will be used)
@return a platform specific String representation of the classpath