refactor(internal/librarian/java): extract logic and struct to derive maven coordinates to file (#5121)

Extracts logic and structs around deriving maven coordinates for various
modules within a Java library into a separate file.

Author: zhumin8

internal/librarian/java/generate.go

@@ -31,9 +31,6 @@ import (
 )
 
 const (
-	cloudPrefix  = "google-cloud-"
-	grpcPrefix   = "grpc-"
-	protoPrefix  = "proto-"
 	commonProtos = "google/cloud/common_resources.proto"
 )
 
@@ -165,27 +162,6 @@ func generateAPI(ctx context.Context, cfg *config.Config, api *config.API, libra
 	return nil
 }
 
-// ensureCloudPrefix returns name with the "google-cloud-" prefix,
-// adding it if not already present.
-func ensureCloudPrefix(name string) string {
-	if !strings.HasPrefix(name, cloudPrefix) {
-		return cloudPrefix + name
-	}
-	return name
-}
-
-func deriveDistributionName(library *config.Library) string {
-	if library.Java != nil && library.Java.DistributionNameOverride != "" {
-		return library.Java.DistributionNameOverride
-	}
-	groupID := "com.google.cloud"
-	if library.Java != nil && library.Java.GroupID != "" {
-		groupID = library.Java.GroupID
-	}
-	artifactID := ensureCloudPrefix(library.Name)
-	return fmt.Sprintf("%s:%s", groupID, artifactID)
-}
-
 var runProtoc = func(ctx context.Context, args []string) error {
 	return command.Run(ctx, "protoc", args...)
 }

internal/librarian/java/generate_test.go

@@ -130,48 +130,6 @@ func TestResolveGAPICOptions(t *testing.T) {
 	}
 }
 
-func TestDeriveDistributionName(t *testing.T) {
-	for _, test := range []struct {
-		name    string
-		library *config.Library
-		want    string
-	}{
-		{
-			name:    "default case",
-			library: &config.Library{Name: "secretmanager"},
-			want:    "com.google.cloud:google-cloud-secretmanager",
-		},
-		{
-			name: "groupID override",
-			library: &config.Library{
-				Name: "secretmanager",
-				Java: &config.JavaModule{GroupID: "com.custom"},
-			},
-			want: "com.custom:google-cloud-secretmanager",
-		},
-		{
-			name: "distributionName override",
-			library: &config.Library{
-				Name: "secretmanager",
-				Java: &config.JavaModule{DistributionNameOverride: "com.google.cloud:google-cloud-secretmanager-v1"},
-			},
-			want: "com.google.cloud:google-cloud-secretmanager-v1",
-		},
-		{
-			name:    "library name already has prefix",
-			library: &config.Library{Name: "google-cloud-secretmanager"},
-			want:    "com.google.cloud:google-cloud-secretmanager",
-		},
-	} {
-		t.Run(test.name, func(t *testing.T) {
-			got := deriveDistributionName(test.library)
-			if got != test.want {
-				t.Errorf("deriveDistributionName() = %q, want %q", got, test.want)
-			}
-		})
-	}
-}
-
 func TestResolveGAPICOptions_MultipleConfigsError(t *testing.T) {
 	for _, test := range []struct {
 		name    string

internal/librarian/java/maven_coordinate.go

@@ -0,0 +1,132 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package java
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/googleapis/librarian/internal/config"
+)
+
+const (
+	googleGroupID   = "com.google"
+	protoGrpcSuffix = ".api.grpc"
+	cloudPrefix     = "google-cloud-"
+	grpcPrefix      = "grpc-"
+	protoPrefix     = "proto-"
+)
+
+var groupInclusions = map[string]bool{
+	"com.google.cloud":     true,
+	"com.google.analytics": true,
+	"com.google.area120":   true,
+}
+
+type coordinate struct {
+	GroupID    string
+	ArtifactID string
+	Version    string
+}
+
+type libCoord struct {
+	gapic  coordinate
+	parent coordinate
+	bom    coordinate
+}
+
+type apiCoord struct {
+	libCoord
+	proto coordinate
+	grpc  coordinate
+}
+
+func deriveLibCoord(library *config.Library) libCoord {
+	distName := deriveDistributionName(library)
+	parts := strings.SplitN(distName, ":", 2)
+	groupID := parts[0]
+	artifactID := groupID
+	if len(parts) == 2 {
+		artifactID = parts[1]
+	}
+	gapic := coordinate{
+		GroupID:    groupID,
+		ArtifactID: artifactID,
+		Version:    library.Version,
+	}
+	return libCoord{
+		gapic: gapic,
+		parent: coordinate{
+			GroupID:    gapic.GroupID,
+			ArtifactID: fmt.Sprintf("%s-parent", gapic.ArtifactID),
+			Version:    gapic.Version,
+		},
+		bom: coordinate{
+			GroupID:    gapic.GroupID,
+			ArtifactID: fmt.Sprintf("%s-bom", gapic.ArtifactID),
+			Version:    gapic.Version,
+		},
+	}
+}
+
+func deriveAPICoord(lc libCoord, version string) apiCoord {
+	protoGrpcGroupID := protoGroupID(lc.gapic.GroupID)
+	return apiCoord{
+		libCoord: lc,
+		proto: coordinate{
+			GroupID:    protoGrpcGroupID,
+			ArtifactID: fmt.Sprintf("%s%s-%s", protoPrefix, lc.gapic.ArtifactID, version),
+			Version:    lc.gapic.Version,
+		},
+		grpc: coordinate{
+			GroupID:    protoGrpcGroupID,
+			ArtifactID: fmt.Sprintf("%s%s-%s", grpcPrefix, lc.gapic.ArtifactID, version),
+			Version:    lc.gapic.Version,
+		},
+	}
+}
+
+// protoGroupID returns the Maven Group ID for the generated proto and gRPC
+// artifacts. It maps the GAPIC library's Group ID to a standard format and
+// checks for special cases in groupInclusions (e.g., mapping
+// "com.google.cloud" to "com.google.api.grpc").
+func protoGroupID(mainArtifactGroupID string) string {
+	prefix := mainArtifactGroupID
+	if groupInclusions[mainArtifactGroupID] {
+		prefix = googleGroupID
+	}
+	return prefix + protoGrpcSuffix
+}
+
+// ensureCloudPrefix returns name with the "google-cloud-" prefix,
+// adding it if not already present.
+func ensureCloudPrefix(name string) string {
+	if !strings.HasPrefix(name, cloudPrefix) {
+		return cloudPrefix + name
+	}
+	return name
+}
+
+func deriveDistributionName(library *config.Library) string {
+	if library.Java != nil && library.Java.DistributionNameOverride != "" {
+		return library.Java.DistributionNameOverride
+	}
+	groupID := "com.google.cloud"
+	if library.Java != nil && library.Java.GroupID != "" {
+		groupID = library.Java.GroupID
+	}
+	artifactID := ensureCloudPrefix(library.Name)
+	return fmt.Sprintf("%s:%s", groupID, artifactID)
+}