@Override
    protected Package getPackage(String name) {
        Package p = super.getPackage(name);
        if (p == null || !isPackageAllowed(p.getName())) {
            return null;
        }
        return p;
    }

    @Override
    protected Package[] getPackages() {
        List<Package> packages = new ArrayList<Package>();
        for (Package p : super.getPackages()) {

         * @param packages list of package prefixes
         */
        public Link(String url, String... packages) {
            throwExceptionIfNull(url, "Url must not be null");
            if (packages.length == 0) {
                throw new InvalidUserDataException("You must specify at least one package!");
            }
            for (String aPackage : packages) {

that pattern (see 'go help packages' for a description of package
patterns). Without a pattern, the argument list applies only to the
packages named on the command line. The flags may be repeated
with different patterns in order to specify different arguments for
different sets of packages. If a package matches patterns given in
multiple flags, the latest match on the command line wins.

	UsageLine: "go list [-f format] [-json] [-m] [list flags] [build flags] [packages]",
	Short:     "list packages or modules",
	Long: `
List lists the named packages, one per line.
The most commonly-used flags are -f and -json, which control the form
of the output printed for each package. Other list flags, documented below,
control more specific details.

The default output shows the package import path:

    bytes
    encoding/json

	`,
}

var HelpPackages = &base.Command{
	UsageLine: "packages",
	Short:     "package lists and patterns",
	Long: `
Many commands apply to a set of packages:

	go <action> [packages]

Usually, [packages] is a list of import paths.

An import path that is a rooted path or that begins with
a . or .. element is interpreted as a file system path and
denotes the package in that directory.

	Dirs    []string // if the pattern is local, directories that potentially contain matching packages
	Pkgs    []string // matching packages (import paths)
	Errs    []error  // errors matching the patterns to packages, NOT errors loading those packages

	// Errs may be non-empty even if len(Pkgs) > 0, indicating that some matching
	// packages could be located but results may be incomplete.

	// i.e., locally vendored packages may not be found.
	// The types package does not call Import if an ImporterFrom
	// is present.
	Importer

	// ImportFrom returns the imported package for the given import
	// path when imported by a package file located in dir.
	// If the import failed, besides returning an error, ImportFrom
	// is encouraged to cache and return a package anyway, if one

	// i.e., locally vendored packages may not be found.
	// The types package does not call Import if an ImporterFrom
	// is present.
	Importer

	// ImportFrom returns the imported package for the given import
	// path when imported by a package file located in dir.
	// If the import failed, besides returning an error, ImportFrom
	// is encouraged to cache and return a package anyway, if one

		// imports. TestStdlib will collect errors once for each package.
		return pkg, nil
	}
	return nil, err
}

// getDirPackage gets the package defined in dir from the future cache.
//
// If this is the first goroutine requesting the package, getDirPackage
// type-checks.
func (c *stdlibChecker) getDirPackage(dir string) (*Package, error) {
	c.mu.Lock()
	fut, ok := c.pkgs[dir]
	if !ok {

	return pmain, ptest, pxtest, err
}

// TestPackagesAndErrors returns three packages:
//   - pmain, the package main corresponding to the test binary (running tests in ptest and pxtest).
//   - ptest, the package p compiled with added "package p" test files.
//   - pxtest, the result of compiling any "package p_test" (external) test files.
//
// If the package has no "package p_test" test files, pxtest will be nil.