1. This is the generator function. It's a "generator function" because it contains `yield` statements inside.
2. By using a `with` block, we make sure that the file-like object is closed after the generator function is done. So, after it finishes sending the response.

public class LayeredMavenOptions<O extends MavenOptions> extends LayeredOptions<O> implements MavenOptions {
    public static MavenOptions layerMavenOptions(Collection<MavenOptions> options) {
        List<MavenOptions> o = options.stream().filter(Objects::nonNull).toList();
        if (o.isEmpty()) {
            throw new IllegalArgumentException("No options specified (or all were null)");
        } else if (o.size() == 1) {
            return o.get(0);

所以 OpenAPI为了相似的目的定义了自己的 <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.3.md#fixed-fields-20" class="external-link" target="_blank">`example`</a> (使用 `example`, 而不是 `examples`), 这也是文档 UI 所使用的 (使用 Swagger UI).

所以，虽然 `example` 不是JSON Schema的一部分，但它是OpenAPI的一部分，这将被文档UI使用。

## 其他信息

 *
 * @since 4.0.0
 */
@Experimental
public interface PathType {
    /**
     * The type for all paths that could not be placed in any of the types requested by a caller.
     * This type can appear in the return value of a call to
     * {@link Session#resolveDependencies resolveDependencies(...)} when at least one dependency

	// such that finally fivs.Versions has
	// all the non-free versions and fivs.FreeVersions has all the free
	// versions.
	n := 0
	for _, fi := range fivs.Versions {
		// filter our tier object delete marker
		if fi.TierFreeVersion() {
			if !inclFreeVersions {
				fivs.FreeVersions = append(fivs.FreeVersions, fi)
			}
		} else {
			if !inclFreeVersions {
				fivs.Versions[n] = fi
			}

/**
 * Resident invoker implementation, specialization of Maven Invoker, but keeps Maven instance resident. This implies, that
 * things like environment, system properties, extensions etc. are loaded only once. It is caller duty to ensure
 * that subsequent call is right for the resident instance (ie no env change or different extension needed).
 * This implementation "pre-populates" MavenContext with pre-existing stuff (except for very first call)

		return r.r.Read(buf)
	}
	if r.lastErr != nil {
		err = r.lastErr
		return n, err
	}
	b := r.throttle.Burst()  // maximum available tokens
	need := len(buf)         // number of bytes requested by caller
	hdr := r.opts.HeaderSize // remaining header bytes
	var tokens int           // number of tokens to request

	if hdr > 0 { // available tokens go towards header first
		if hdr < b { // all of header can be accommodated

     * from any repository but are present among the set of specified projects will not cause an exception. Instead,
     * those unresolved artifacts will be returned in the result set, allowing the caller to take special care of
     * artifacts that haven't been build yet.
     *
     * @param projects The projects whose dependencies should be resolved, may be {@code null}.

        if (planStep.isPresent() && planStep.get().status.get() == BuildStep.PLANNING) {
            writer.accept("Build plan will be lazily computed");
        } else {
            plan.steps(project)
                    .filter(step ->
                            step.phase != null && step.executions().findAny().isPresent())
                    .sorted(Comparator.comparingInt(plan.sortedNodes()::indexOf))
                    .forEach(step -> {

				}
			}
		}()
		o.ID = ""
	}

	if contextCanceled(ctx) {
		return entries, ctx.Err()
	}
	// Do listing in-place.
	// Create output for our results.
	// Create filter for results.
	o.debugln("Raw List", o)
	filterCh := make(chan metaCacheEntry, o.Limit)
	listCtx, cancelList := context.WithCancel(ctx)
	filteredResults := o.gatherResults(listCtx, filterCh)
	var wg sync.WaitGroup