import java.util.Map;

import org.apache.maven.toolchain.model.ToolchainModel;

/**
 * a private contract between the toolchains plugin and the components.
 */
public interface ToolchainPrivate extends Toolchain {

    /**
     * Let the toolchain decide if it matches requirements defined
     * in the toolchain plugin configuration.

        ToolchainPrivate basicToolchain = mock(ToolchainPrivate.class);
        when(toolchainFactory_basicType.createDefaultToolchain()).thenReturn(basicToolchain);
        ToolchainPrivate rareToolchain = mock(ToolchainPrivate.class);
        when(toolchainFactory_rareType.createDefaultToolchain()).thenReturn(rareToolchain);

        // execute

        MavenSession s = InternalMavenSession.from(session).getMavenSession();
        org.apache.maven.toolchain.ToolchainPrivate tc =
                (org.apache.maven.toolchain.ToolchainPrivate) ((ToolchainWrapper) toolchain).toolchain;
        toolchainManagerPrivate.storeToolchainToBuildContext(tc, s);
    }

            }

            // add default toolchain
            ToolchainPrivate tool = fact.createDefaultToolchain();
            if (tool != null) {
                toRet.add(tool);
            }
        }

        return toRet.toArray(new ToolchainPrivate[0]);
    }

    @Override
    public void storeToolchainToBuildContext(ToolchainPrivate toolchain, MavenSession session) {

        executionRequest.setToolchains(toolchainModels);
        when(session.getRequest()).thenReturn(executionRequest);
        ToolchainPrivate basicPrivate = mock(ToolchainPrivate.class);
        when(basicPrivate.matchesRequirements(ArgumentMatchers.<String, String>anyMap()))
                .thenReturn(false)
                .thenReturn(true);

import org.apache.maven.toolchain.RequirementMatcher;
import org.apache.maven.toolchain.RequirementMatcherFactory;
import org.apache.maven.toolchain.ToolchainFactory;
import org.apache.maven.toolchain.ToolchainPrivate;
import org.apache.maven.toolchain.model.ToolchainModel;
import org.codehaus.plexus.util.xml.Xpp3Dom;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * JDK toolchain factory.

    /**
     * Create instance of toolchain.
     **/
    ToolchainPrivate createToolchain(ToolchainModel model) throws MisconfiguredToolchainException;

    /**
     * Returns the default instance of the particular type of toolchain, can return <code>null</code>
     * if not applicable.
     * TODO keep around??
     **/
    ToolchainPrivate createDefaultToolchain();

     *
     * @param type the type, must not be {@code null}
     * @param context the Maven session, must not be {@code null}
     * @since 3.0 (addition of the <code>MavenSession</code> parameter)
     */
    ToolchainPrivate[] getToolchainsForType(String type, MavenSession context) throws MisconfiguredToolchainException;

    /**
     * Stores the toolchain into build context for later use by toolchain-aware plugins.
     *

            } else {
                for (ToolchainModel model : models) {
                    try {
                        ToolchainPrivate toolchain = fact.createToolchain(model);
                        if (requirements == null || toolchain.matchesRequirements(requirements)) {
                            toolchains.add(toolchain);
                        }

 * to avoid rewriting usual code.
 *
 * @since 2.0.9
 */
public abstract class DefaultToolchain // should have been AbstractToolchain...
implements Toolchain, ToolchainPrivate {
    private final Logger logger;

    private String type;

    private Map<String, RequirementMatcher> provides = new HashMap<>();

    public static final String KEY_TYPE = "type"; // NOI18N