fix(tool/cmd/migrate): derive APIShortnameOverride instead of hardcode (#5527)

This change refactors how api_shortname is determined and migrated for
Java libraries to ensure behavioral parity with the hermetic build while
minimizing configuration noise.

Migration Script (java.go) now mimics the derives the shortname logic
(using serviceconfig.Find) and only adds an APIShortnameOverride to
librarian.yaml if the legacy configuration differs. This replaces the
hardcoded map in java_module.go.
Updated migration tests to use testdata (e.g., secretmanager, places) to
verify both standard discovery and discrepancy-based overriding.

Confirmed local running migrate, the previous hardcoded overrides are
kept.

Fix #5296

Author: zhumin8

internal/testdata/googleapis/google/maps/places/v1/places_v1.yaml

@@ -0,0 +1,6 @@
+type: google.api.Service
+config_version: 3
+name: places.googleapis.com
+title: Places API (New)
+publishing:
+  api_short_name: places

tool/cmd/migrate/java.go

@@ -30,6 +30,7 @@ import (
 	"github.com/googleapis/librarian/internal/config"
 	"github.com/googleapis/librarian/internal/librarian"
 	"github.com/googleapis/librarian/internal/librarian/java"
+	"github.com/googleapis/librarian/internal/serviceconfig"
 	"github.com/googleapis/librarian/internal/yaml"
 )
 
@@ -294,6 +295,17 @@ func buildConfig(gen *GenerationConfig, repoPath string, src *config.Source, ver
 				TransportOverride:            l.Transport,
 			},
 		}
+		if len(apis) > 0 {
+			derivedShortName := name
+			serviceconfig.SortAPIs(apis)
+			api, err := serviceconfig.Find(src.Dir, apis[0].Path, config.LanguageJava)
+			if err == nil && api.ShortName != "" {
+				derivedShortName = api.ShortName
+			}
+			if derivedShortName != l.APIShortName {
+				lib.Java.APIShortnameOverride = l.APIShortName
+			}
+		}
 		if override, ok := keepOverride[lib.Name]; ok {
 			lib.Keep = override
 		} else {
@@ -303,9 +315,6 @@ func buildConfig(gen *GenerationConfig, repoPath string, src *config.Source, ver
 			}
 			lib.Keep = keep
 		}
-		if shortnameOverride, ok := apiShortnameOverrides[lib.Name]; ok {
-			lib.Java.APIShortnameOverride = shortnameOverride
-		}
 		libs = append(libs, lib)
 	}
 	if len(libs) == 0 {

tool/cmd/migrate/java_module.go

@@ -15,18 +15,6 @@
 package main
 
 var (
-	apiShortnameOverrides = map[string]string{
-		"beyondcorp-appconnections":          "beyondcorp-appconnections",
-		"beyondcorp-appconnectors":           "beyondcorp-appconnectors",
-		"beyondcorp-appgateways":             "beyondcorp-appgateways",
-		"beyondcorp-clientconnectorservices": "beyondcorp-clientconnectorservices",
-		"beyondcorp-clientgateways":          "beyondcorp-clientgateways",
-		"dialogflow-cx":                      "dialogflow-cx",
-		"distributedcloudedge":               "distributedcloudedge",
-		"gke-backup":                         "gke-backup",
-		"apigee-registry":                    "apigee-registry",
-	}
-
 	excludedSamplesLibraries = map[string]bool{
 		"bigquerystorage":   true,
 		"datastore":         true,

tool/cmd/migrate/java_test.go

@@ -190,29 +190,29 @@ func TestBuildConfig(t *testing.T) {
 			gen: &GenerationConfig{
 				Libraries: []LibraryConfig{
 					{
-						LibraryName:  "language-v1",
-						APIShortName: "language",
+						LibraryName:  "secretmanager-v1",
+						APIShortName: "secretmanager",
 						GAPICs: []GAPICConfig{
-							{ProtoPath: "google/cloud/language/v1"},
+							{ProtoPath: "google/cloud/secretmanager/v1"},
 						},
 					},
 				},
 			},
-			src: &config.Source{},
+			src: &config.Source{Dir: "../../../internal/testdata/googleapis"},
 			want: &config.Config{
 				Language: "java",
 				Repo:     "googleapis/google-cloud-java",
 				Default: &config.Default{
 					Java: &config.JavaModule{},
 				},
 				Sources: &config.Sources{
-					Googleapis: &config.Source{},
+					Googleapis: &config.Source{Dir: "../../../internal/testdata/googleapis"},
 				},
 				Libraries: []*config.Library{
 					{
-						Name: "language-v1",
+						Name: "secretmanager-v1",
 						APIs: []*config.API{
-							{Path: "google/cloud/language/v1"},
+							{Path: "google/cloud/secretmanager/v1"},
 						},
 						Java: &config.JavaModule{},
 					},
@@ -429,24 +429,33 @@ func TestBuildConfig(t *testing.T) {
 			name: "api shortname overrides",
 			gen: &GenerationConfig{
 				Libraries: []LibraryConfig{
-					{APIShortName: "beyondcorp-appconnections"},
+					{
+						LibraryName:  "maps-places",
+						APIShortName: "maps-places",
+						GAPICs: []GAPICConfig{
+							{ProtoPath: "google/maps/places/v1"},
+						},
+					},
 				},
 			},
-			src: &config.Source{},
+			src: &config.Source{Dir: "../../../internal/testdata/googleapis"},
 			want: &config.Config{
 				Language: "java",
 				Repo:     "googleapis/google-cloud-java",
 				Default: &config.Default{
 					Java: &config.JavaModule{},
 				},
 				Sources: &config.Sources{
-					Googleapis: &config.Source{},
+					Googleapis: &config.Source{Dir: "../../../internal/testdata/googleapis"},
 				},
 				Libraries: []*config.Library{
 					{
-						Name: "beyondcorp-appconnections",
+						Name: "maps-places",
+						APIs: []*config.API{
+							{Path: "google/maps/places/v1"},
+						},
 						Java: &config.JavaModule{
-							APIShortnameOverride: "beyondcorp-appconnections",
+							APIShortnameOverride: "maps-places",
 						},
 					},
 				},