// The returned EnvSet has the same compatibility version as the EnvSet that was extended.
//
// Extend is an expensive operation and each call to Extend that adds DeclTypes increases
// the depth of a chain of resolvers. For these reasons, calls to Extend should be kept
// to a minimum.
//
// Some best practices:
//
//   - Minimize calls Extend when handling API requests. Where possible, call Extend

		// but that is a detail of the specific lookup mechanism.
		// Other lookups might allow broader name syntax
		// (for example Multicast DNS allows UTF-8; see RFC 6762).
		// For consistency with libc resolvers, report no such host.
		return dnsmessage.Parser{}, "", newDNSError(errNoSuchHost, name, "")
	}

	if conf == nil {
		conf = getSystemDNSConfig()
	}

	var (
		p      dnsmessage.Parser

	dnsConfig, err := dns.ClientConfigFromFile(resolvConf)
	if err != nil {
		log.Warnf("failed to load %s: %v", resolvConf, err)
		return nil, err
	}

	// Unlike traditional DNS resolvers, we do not need to append the search
	// namespace to a given query and try to resolve it. This is because the
	// agent acts as a DNS interceptor for DNS queries made by the application.

include::sample[dir="snippets/java/toolchain-foojay/groovy/",files="settings.gradle[tags=plugin-application]"]
====

In general, when applying toolchain resolver plugins, the toolchain download resolvers provided by them also need to be configured.
Let's illustrate with an example.
Consider two toolchain resolver plugins applied by the build:

	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/resolver"
	"google.golang.org/grpc/serviceconfig"
	"google.golang.org/grpc/status"
	xdsgrpc "google.golang.org/grpc/xds" // To install the xds resolvers and balancers.
	"google.golang.org/protobuf/proto"

	networking "istio.io/api/networking/v1alpha3"
	security "istio.io/api/security/v1beta1"
	"istio.io/istio/pilot/pkg/features"
	"istio.io/istio/pilot/pkg/model"

	if len(composedSearch) > maxDNSSearchPaths {
		composedSearch = composedSearch[:maxDNSSearchPaths]
		limitsExceeded = true
	}

	// In some DNS resolvers(e.g. glibc 2.28), DNS resolving causes abort() if there is a
	// search path exceeding 255 characters. We have to filter them out.
	l := 0
	for _, search := range composedSearch {

						}
					}
					if tt.expectExternalResolution {
						// just make sure that the response has a valid DNS response from upstream resolvers
						if res.Rcode != dns.RcodeSuccess {
							t.Errorf("upstream dns resolution for %s failed: %v", tt.host, res)
						}
					} else {

	// DNS search list), this option causes such errors to abort the
	// whole query instead of returning a partial result. This is
	// not enabled by default because it may affect compatibility
	// with resolvers that process AAAA queries incorrectly.
	StrictErrors bool

	// Dial optionally specifies an alternate dialer for use by
	// Go's built-in DNS resolver to make TCP and UDP connections

	glink.AddUint32(ctxt.Arch, 0x7800f082) // srdi r0,r0,2

	// Load the PC-rel offset of ".plt - 1b", and add it to 1b.
	// This is stored after this stub and before the resolvers.
	glink.AddUint32(ctxt.Arch, 0xe98b0000) // ld r12,res_0-1b-8(r11)
	glink.AddUint32(ctxt.Arch, 0x7d6b6214) // add r11,r11,r12

	// Load r12 = dynamic resolver address and r11 = DSO

                    services.get(FileCollectionFactory.class),
                    services.get(DependencyMetaDataProvider.class),
                    new UnknownProjectFinder("Detached resolvers do not support resolving projects"),
                    new DetachedDependencyResolutionDomainObjectContext(services.get(DomainObjectContext.class))
                );
            }
        });