liquibase-maven-plugin/src/main/java/org/liquibase/maven/plugins/AbstractLiquibaseMojo.java
protected ClassLoader getClassLoaderIncludingProjectClasspath() throws MojoExecutionException {
        try {
            List classpathElements = project.getCompileClasspathElements();
            classpathElements.add(project.getBuild().getOutputDirectory());
            URL urls[] = new URL[classpathElements.size()];
            for (int i = 0; i < classpathElements.size(); ++i) {
                urls[i] = new File((String) classpathElements.get(i)).toURI().toURL();
            }
            return new URLClassLoader(urls, getMavenArtifactClassLoader());
        } catch (Exception e) {
            throw new MojoExecutionException("Failed to create project classloader", e);
        }
    }
protected ClassLoader getClassLoaderIncludingProjectClasspath() throws MojoExecutionException {
        try {
            List classpathElements = project.getCompileClasspathElements();
            classpathElements.add(project.getBuild().getOutputDirectory());
            URL urls[] = new URL[classpathElements.size()];
            for (int i = 0; i < classpathElements.size(); ++i) {
                urls[i] = new File((String) classpathElements.get(i)).toURI().toURL();
            }
            return new URLClassLoader(urls, getMavenArtifactClassLoader());
        } catch (Exception e) {
            throw new MojoExecutionException("Failed to create project classloader", e);
        }
    }
Returns an isolated classloader.

@return ClassLoader
@noinspection unchecked