Cleanup usages of resolver.Target's Scheme and Authority (#5761)

internal/resolver/dns/dns_resolver.go

@@ -140,10 +140,10 @@ func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts
 		disableServiceConfig: opts.DisableServiceConfig,
 	}
 
-	if target.Authority == "" {
+	if target.URL.Host == "" {
 		d.resolver = defaultResolver
 	} else {
-		d.resolver, err = customAuthorityResolver(target.Authority)
+		d.resolver, err = customAuthorityResolver(target.URL.Host)
 		if err != nil {
 			return nil, err
 		}

internal/resolver/dns/dns_resolver_test.go

@@ -23,6 +23,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"net/url"
 	"os"
 	"reflect"
 	"strings"
@@ -1439,7 +1440,12 @@ func TestCustomAuthority(t *testing.T) {
 
 		b := NewBuilder()
 		cc := &testClientConn{target: "foo.bar.com", errChan: make(chan error, 1)}
-		r, err := b.Build(resolver.Target{Endpoint: "foo.bar.com", Authority: a.authority}, cc, resolver.BuildOptions{})
+		target := resolver.Target{
+			Endpoint:  "foo.bar.com",
+			Authority: a.authority,
+			URL:       url.URL{Host: a.authority},
+		}
+		r, err := b.Build(target, cc, resolver.BuildOptions{})
 
 		if err == nil {
 			r.Close()

internal/resolver/unix/unix.go

@@ -34,8 +34,8 @@ type builder struct {
 }
 
 func (b *builder) Build(target resolver.Target, cc resolver.ClientConn, _ resolver.BuildOptions) (resolver.Resolver, error) {
-	if target.Authority != "" {
-		return nil, fmt.Errorf("invalid (non-empty) authority: %v", target.Authority)
+	if target.URL.Host != "" {
+		return nil, fmt.Errorf("invalid (non-empty) authority: %v", target.URL.Host)
 	}
 
 	// gRPC was parsing the dial target manually before PR #4817, and we

stream.go

@@ -416,7 +416,7 @@ func (cs *clientStream) newAttemptLocked(isTransparent bool) (*csAttempt, error)
 		ctx = trace.NewContext(ctx, trInfo.tr)
 	}
 
-	if cs.cc.parsedTarget.Scheme == "xds" {
+	if cs.cc.parsedTarget.URL.Scheme == "xds" {
 		// Add extra metadata (metadata that will be added by transport) to context
 		// so the balancer can see them.
 		ctx = grpcutil.WithExtraMetadata(ctx, metadata.Pairs(