* @since 3.0
 */
public class EnvironmentUtils {

    private static Properties envVars;

    /**
     * Adds the environment variables in the form of properties whose keys are prefixed with {@code env.}, e.g. {@code
     * env.PATH}. Unlike native environment variables, properties are always case-sensitive. For the sake of
     * determinism, the environment variable names will be normalized to upper case on platforms with case-insensitive

    }

    @Provides
    static Session newSession(RepositorySystem system, Lookup lookup) {
        Map<String, String> properties = new HashMap<>();
        // Env variables prefixed with "env."
        System.getenv().forEach((k, v) -> properties.put("env." + k, v));
        // Java System properties
        System.getProperties().forEach((k, v) -> properties.put(k.toString(), v.toString()));

        valueSources.add(new AbstractValueSource(false) {
            @Override
            public Object getValue(String expression) {
                return request.getSystemProperties().get("env." + expression);
            }
        });

        valueSources.add(prefixlessObjectBasedValueSource);

        return valueSources;
    }

     * Returns immutable system properties to use for interpolation. The system properties are collected from the
     * runtime environment such as {@link System#getProperties()} and environment variables
     * (prefixed with {@code env.}).
     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

    /**

        valueSources.add(new AbstractValueSource(false) {

            public Object getValue(String expression) {
                return config.getExecutionProperties().getProperty("env." + expression);
            }
        });
        valueSources.add(modelValueSource2);

        return valueSources;
    }

    protected List<InterpolationPostProcessor> createPostProcessors(

        tm1.addProvide("version", "1.5");
        tm1.addProvide("vendor", "sun");
        Xpp3Dom configuration1 = new Xpp3Dom("configuration");
        Xpp3Dom jdkHome1 = new Xpp3Dom("jdkHome");
        jdkHome1.setValue("${env.JAVA_HOME}");
        configuration1.addChild(jdkHome1);
        tm1.setConfiguration(configuration1);

        ToolchainModel tm2 = new ToolchainModel();
        tm1.setType("jdk");

        sessionBuilder.setArtifactTypeRegistry(new TypeRegistryAdapter(typeRegistry)); // dynamic
        sessionBuilder.setCache(request.getRepositoryCache());

        // this map is read ONLY to get config from (profiles + env + system + user)
        Map<String, String> mergedProps = createMergedProperties(request);

        // configProps map is kept "pristine", is written ONLY, the mandatory resolver config