diff --git a/builders/t9n/index.ts b/builders/t9n/index.ts
index 373b10a..34ace1a 100644
--- a/builders/t9n/index.ts
+++ b/builders/t9n/index.ts
@@ -42,16 +42,19 @@ export async function t9n(options: Options, context: BuilderContext): Promise<Bu
 
   const translationContext = await TranslationFactory.createTranslationContext({
     logger: context.logger,
-    source: translationFile,
+    project: context.target ? context.target.project : 'unknown',
+    sourceFile: translationFile,
     targetPath: targetTranslationPath,
     targets: targetFiles.map(f => join(targetTranslationPath, f)),
     includeContextInTarget: options.includeContextInTarget,
     encoding: options.encoding || 'UTF-8'
   });
-  const server = new TranslationServer(context.logger, translationContext, options.port);
-  await server.shutdown.toPromise();
+  const server = new TranslationServer(context.logger, translationContext);
+  server.listen(options.port, () =>
+    context.logger.info(`Translation server started: http://localhost:${options.port}\n`)
+  );
 
-  return { success: true };
+  return new Promise(() => {});
 }
 
 function isFile(path: string) {
diff --git a/builders/t9n/server/responses/root-response.ts b/builders/t9n/server/responses/root-response.ts
index 9e81b01..78bb007 100644
--- a/builders/t9n/server/responses/root-response.ts
+++ b/builders/t9n/server/responses/root-response.ts
@@ -4,6 +4,8 @@ import { Hal, HalLink, Links } from '../hal';
 import { UrlFactory } from '../url-factory';
 
 export class RootResponse implements Hal {
+  project: string;
+  sourceFile: string;
   sourceLanguage: string;
   languages: string[];
   unitCount: number;
@@ -11,6 +13,8 @@ export class RootResponse implements Hal {
   _embedded?: { [key: string]: unknown };
 
   constructor(context: TranslationContext, urlFactory: UrlFactory) {
+    this.project = context.project;
+    this.sourceFile = context.source.file;
     this.sourceLanguage = context.source.language;
     this.languages = context.languages;
     this.unitCount = context.source.units.length;
diff --git a/builders/t9n/server/translation-server.ts b/builders/t9n/server/translation-server.ts
index 196102f..c84415d 100644
--- a/builders/t9n/server/translation-server.ts
+++ b/builders/t9n/server/translation-server.ts
@@ -5,9 +5,8 @@ import { readFile } from 'fs';
 import Koa from 'koa';
 import koaBody from 'koa-body';
 import koaStatic from 'koa-static';
-import { Server, Socket } from 'net';
+import { Server } from 'net';
 import { join } from 'path';
-import { Observable, Subject } from 'rxjs';
 import { promisify } from 'util';
 
 import { TranslationContext, TranslationTargetUnit } from '../translation';
@@ -34,32 +33,18 @@ import {
 const readFileAsync = promisify(readFile);
 
 export class TranslationServer {
-  readonly shutdown: Observable<void>;
-
-  private _connections: { [key: string]: Socket } = {};
-  private _shutdown = new Subject<void>();
-  private _server: Server;
+  private readonly _server: Koa<any, any>;
 
   constructor(
     private readonly _logger: logging.LoggerApi,
-    private readonly _context: TranslationContext,
-    private readonly _port: number
+    private readonly _context: TranslationContext
   ) {
     this._logger.info(`Current languages: ${this._context.languages.join(', ')}\n`);
-    this._server = this._createServer();
-    this.shutdown = this._shutdown.asObservable();
+    this._server = this._createApp();
   }
 
-  private _createServer() {
-    const server = this._createApp().listen(this._port, () =>
-      this._logger.info(`Translation server started: http://localhost:${this._port}\n`)
-    );
-    server.on('connection', connection => {
-      const key = `${connection.remoteAddress}:${connection.remotePort}`;
-      this._connections[key] = connection;
-      connection.on('close', () => delete this._connections[key]);
-    });
-    return server;
+  listen(port: number, listeningListener?: () => void): Server {
+    return this._server.listen(port, listeningListener);
   }
 
   private _createApp() {
@@ -84,16 +69,6 @@ export class TranslationServer {
       options?: Router.UrlOptionsQuery
     ) => `${ctx.protocol}://${ctx.host}${ctx.router.url(name, params, options)}`;
     return new Router({ prefix: '/api' })
-      .delete('/', async () => {
-        this._logger.info('\nClosing connections');
-        await new Promise((resolve, reject) => {
-          this._server.close(err => (err ? reject(err) : resolve()));
-          Object.values(this._connections).forEach(c => c.destroy());
-        });
-        this._logger.info('Shutting down translation server');
-        this._shutdown.next();
-        this._shutdown.complete();
-      })
       .get(ROOT_ROUTE, '/', ctx => {
         ctx.body = new RootResponse(this._context, toUrlFactory(ctx));
       })
diff --git a/builders/t9n/translation/debounce-scheduler.ts b/builders/t9n/translation/debounce-scheduler.ts
new file mode 100644
index 0000000..0fcf5be
--- /dev/null
+++ b/builders/t9n/translation/debounce-scheduler.ts
@@ -0,0 +1,20 @@
+export class DebounceScheduler<T> {
+  private readonly _scheduleMap = new Map<T, NodeJS.Timeout>();
+
+  constructor(
+    private readonly _action: (trigger: T) => Promise<void>,
+    private readonly _debounceTime = 500
+  ) {}
+
+  schedule(trigger: T) {
+    const entry = this._scheduleMap.get(trigger);
+    if (entry !== undefined) {
+      clearTimeout(entry);
+    }
+
+    this._scheduleMap.set(
+      trigger,
+      setTimeout(() => this._action(trigger), this._debounceTime)
+    );
+  }
+}
diff --git a/builders/t9n/translation/deserialization/translation-deserializer.ts b/builders/t9n/translation/deserialization/translation-deserializer.ts
index 5496783..fb1a378 100644
--- a/builders/t9n/translation/deserialization/translation-deserializer.ts
+++ b/builders/t9n/translation/deserialization/translation-deserializer.ts
@@ -6,12 +6,12 @@ export interface TranslationDeserializer {
     file: string,
     encoding: string
   ): Promise<{
-    sourceLanguage: string;
+    language: string;
     original: string;
     unitMap: Map<string, TranslationSourceUnit>;
   }>;
   deserializeTarget(
     file: string,
     encoding: string
-  ): Promise<{ targetLanguage: string; unitMap: Map<string, TranslationTargetUnit> }>;
+  ): Promise<{ language: string; unitMap: Map<string, TranslationTargetUnit> }>;
 }
diff --git a/builders/t9n/translation/deserialization/xlf-deserializer-base.ts b/builders/t9n/translation/deserialization/xlf-deserializer-base.ts
index 5670353..9801865 100644
--- a/builders/t9n/translation/deserialization/xlf-deserializer-base.ts
+++ b/builders/t9n/translation/deserialization/xlf-deserializer-base.ts
@@ -17,7 +17,7 @@ export abstract class XlfDeserializerBase implements TranslationDeserializer {
     file: string,
     encoding: string
   ): Promise<{
-    sourceLanguage: string;
+    language: string;
     original: string;
     unitMap: Map<string, TranslationSourceUnit>;
   }>;
@@ -25,7 +25,7 @@ export abstract class XlfDeserializerBase implements TranslationDeserializer {
   abstract deserializeTarget(
     file: string,
     encoding: string
-  ): Promise<{ targetLanguage: string; unitMap: Map<string, TranslationTargetUnit> }>;
+  ): Promise<{ language: string; unitMap: Map<string, TranslationTargetUnit> }>;
 
   protected async _createDocument(file: string, encoding: string) {
     const content = await readFileAsync(file, encoding || 'utf8');
diff --git a/builders/t9n/translation/deserialization/xlf-deserializer.ts b/builders/t9n/translation/deserialization/xlf-deserializer.ts
index 3469d70..b96e319 100644
--- a/builders/t9n/translation/deserialization/xlf-deserializer.ts
+++ b/builders/t9n/translation/deserialization/xlf-deserializer.ts
@@ -7,7 +7,7 @@ export class XlfDeserializer extends XlfDeserializerBase {
   async deserializeSource(file: string, encoding: string) {
     const doc = await this._createDocument(file, encoding);
     const fileNode = this._getFileNode(doc);
-    const sourceLanguage = fileNode.getAttribute('source-language')!;
+    const language = fileNode.getAttribute('source-language')!;
     const original = fileNode.getAttribute('original') || '';
     const unitMap = Array.from(fileNode.getElementsByTagName('trans-unit'))
       .map(u => this._deserializeSourceUnit(u))
@@ -15,21 +15,21 @@ export class XlfDeserializer extends XlfDeserializerBase {
         (current, next) => current.set(next.id, next),
         new Map<string, TranslationSourceUnit>()
       );
-    return { sourceLanguage, original, unitMap };
+    return { language, original, unitMap };
   }
 
   async deserializeTarget(file: string, encoding: string) {
     const doc = await this._createDocument(file, encoding);
     const fileNode = this._getFileNode(doc);
-    const targetLanguage = fileNode.getAttribute('target-language')!;
-    this._assertTargetLanguage(targetLanguage, file);
+    const language = fileNode.getAttribute('target-language')!;
+    this._assertTargetLanguage(language, file);
     const unitMap = Array.from(fileNode.getElementsByTagName('trans-unit'))
       .map(u => this._deserializeTargetUnit(u))
       .reduce(
         (current, next) => current.set(next.id, next),
         new Map<string, TranslationTargetUnit>()
       );
-    return { targetLanguage, unitMap };
+    return { language, unitMap };
   }
 
   protected _assertXliff(doc: Document) {
diff --git a/builders/t9n/translation/deserialization/xlf2-deserializer.ts b/builders/t9n/translation/deserialization/xlf2-deserializer.ts
index 16bfe9b..f543b08 100644
--- a/builders/t9n/translation/deserialization/xlf2-deserializer.ts
+++ b/builders/t9n/translation/deserialization/xlf2-deserializer.ts
@@ -6,7 +6,7 @@ import { XlfDeserializerBase } from './xlf-deserializer-base';
 export class Xlf2Deserializer extends XlfDeserializerBase {
   async deserializeSource(file: string, encoding: string) {
     const doc = await this._createDocument(file, encoding);
-    const sourceLanguage = doc.documentElement.getAttribute('srcLang')!;
+    const language = doc.documentElement.getAttribute('srcLang')!;
     const fileNode = this._getFileNode(doc);
     const original = fileNode.getAttribute('original') || '';
     const unitMap = Array.from(fileNode.childNodes)
@@ -16,13 +16,13 @@ export class Xlf2Deserializer extends XlfDeserializerBase {
         (current, next) => current.set(next.id, next),
         new Map<string, TranslationSourceUnit>()
       );
-    return { sourceLanguage, original, unitMap };
+    return { language, original, unitMap };
   }
 
   async deserializeTarget(file: string, encoding: string) {
     const doc = await this._createDocument(file, encoding);
-    const targetLanguage = doc.documentElement.getAttribute('trgLang')!;
-    this._assertTargetLanguage(targetLanguage, file);
+    const language = doc.documentElement.getAttribute('trgLang')!;
+    this._assertTargetLanguage(language, file);
     const fileNode = this._getFileNode(doc);
     const unitMap = Array.from(fileNode.childNodes)
       .filter(c => c.nodeName === 'unit')
@@ -31,7 +31,7 @@ export class Xlf2Deserializer extends XlfDeserializerBase {
         (current, next) => current.set(next.id, next),
         new Map<string, TranslationTargetUnit>()
       );
-    return { targetLanguage, unitMap };
+    return { language, unitMap };
   }
 
   protected _assertXliff(doc: Document) {
diff --git a/builders/t9n/translation/serialization/translation-serializer.ts b/builders/t9n/translation/serialization/translation-serializer.ts
index 5a00d3d..8610b3d 100644
--- a/builders/t9n/translation/serialization/translation-serializer.ts
+++ b/builders/t9n/translation/serialization/translation-serializer.ts
@@ -2,7 +2,6 @@ import { TranslationTarget } from '../translation-target';
 
 export interface TranslationSerializer {
   serializeTarget(
-    file: string,
     target: TranslationTarget,
     options: {
       encoding: string;
diff --git a/builders/t9n/translation/serialization/xlf-serializer.ts b/builders/t9n/translation/serialization/xlf-serializer.ts
index a1ca409..7b6c8b6 100644
--- a/builders/t9n/translation/serialization/xlf-serializer.ts
+++ b/builders/t9n/translation/serialization/xlf-serializer.ts
@@ -11,7 +11,6 @@ const writeFileAsync = promisify(writeFile);
 
 export class XlfSerializer implements TranslationSerializer {
   async serializeTarget(
-    file: string,
     target: TranslationTarget,
     options: {
       encoding: string;
@@ -40,7 +39,7 @@ ${units
   </file>
 </xliff>
 `;
-    await writeFileAsync(file, content + EOL, options.encoding);
+    await writeFileAsync(target.file, content + EOL, options.encoding);
   }
 
   private _transformState(state: string) {
diff --git a/builders/t9n/translation/serialization/xlf2-serializer.ts b/builders/t9n/translation/serialization/xlf2-serializer.ts
index ef2a5cc..602513e 100644
--- a/builders/t9n/translation/serialization/xlf2-serializer.ts
+++ b/builders/t9n/translation/serialization/xlf2-serializer.ts
@@ -11,7 +11,6 @@ const writeFileAsync = promisify(writeFile);
 
 export class Xlf2Serializer implements TranslationSerializer {
   async serializeTarget(
-    file: string,
     target: TranslationTarget,
     options: {
       encoding: string;
@@ -40,7 +39,7 @@ ${units
   </file>
 </xliff>
 `;
-    await writeFileAsync(file, content + EOL, options.encoding);
+    await writeFileAsync(target.file, content + EOL, options.encoding);
   }
 
   private _serializeNotes(unit: TranslationTargetUnit, target: TranslationTarget) {
diff --git a/builders/t9n/translation/translation-context-configuration.ts b/builders/t9n/translation/translation-context-configuration.ts
index f2f416d..d29b6a7 100644
--- a/builders/t9n/translation/translation-context-configuration.ts
+++ b/builders/t9n/translation/translation-context-configuration.ts
@@ -1,13 +1,18 @@
+import { logging } from '@angular-devkit/core';
+
 import { TranslationSerializer } from './serialization/translation-serializer';
 import { TranslationSource } from './translation-source';
 import { TranslationTarget } from './translation-target';
 
 export interface TranslationContextConfiguration {
+  logger: logging.LoggerApi;
+  project: string;
   encoding: string;
   includeContextInTarget: boolean;
   source: TranslationSource;
+  sourceFile: string;
   targets: Map<string, TranslationTarget>;
   serializer: TranslationSerializer;
   original: string;
-  filenameFactory: (target: TranslationTarget) => string;
+  filenameFactory: (language: string) => string;
 }
diff --git a/builders/t9n/translation/translation-context.ts b/builders/t9n/translation/translation-context.ts
index 7b68f0f..c5e7335 100644
--- a/builders/t9n/translation/translation-context.ts
+++ b/builders/t9n/translation/translation-context.ts
@@ -1,7 +1,6 @@
 import { logging } from '@angular-devkit/core';
-import { Subject } from 'rxjs';
-import { debounceTime, map, switchMap } from 'rxjs/operators';
 
+import { DebounceScheduler } from './debounce-scheduler';
 import { TranslationSerializer } from './serialization/translation-serializer';
 import { TranslationContextConfiguration } from './translation-context-configuration';
 import { TranslationSource } from './translation-source';
@@ -9,8 +8,11 @@ import { TranslationTarget } from './translation-target';
 import { TranslationTargetUnit } from './translation-target-unit';
 
 export class TranslationContext {
+  readonly project: string;
   readonly source: TranslationSource;
+  readonly sourceFile: string;
 
+  private readonly _logger: logging.LoggerApi;
   private readonly _serializer: TranslationSerializer;
   private readonly _targets: Map<string, TranslationTarget>;
   private readonly _options: {
@@ -18,22 +20,27 @@ export class TranslationContext {
     original: string;
     includeContextInTarget: boolean;
   };
-  private readonly _filenameFactory: (target: TranslationTarget) => string;
-  private readonly _serializeScheduler = new Map<string, Subject<void>>();
+  private readonly _filenameFactory: (language: string) => string;
+  private readonly _serializeScheduler: DebounceScheduler<string>;
 
   get languages() {
     return Array.from(this._targets.keys()).sort();
   }
 
-  constructor(
-    private readonly _logger: logging.LoggerApi,
-    configuration: TranslationContextConfiguration
-  ) {
-    this._serializer = configuration.serializer;
+  constructor(configuration: TranslationContextConfiguration) {
+    this.project = configuration.project;
     this.source = configuration.source;
+    this.sourceFile = configuration.sourceFile;
+    this._logger = configuration.logger;
+    this._serializer = configuration.serializer;
     this._targets = configuration.targets;
     this._filenameFactory = configuration.filenameFactory;
     this._options = { ...configuration };
+    this._serializeScheduler = new DebounceScheduler<string>(async language => {
+      const target = this._targets.get(language)!;
+      await this._serializer.serializeTarget(target, this._options);
+      this._logger.info(`${this._timestamp()}: Updated ${target.file}`);
+    });
   }
 
   target(language: string) {
@@ -45,9 +52,9 @@ export class TranslationContext {
       throw new Error(`${language} already exists as target!`);
     }
 
-    const target = new TranslationTarget(this.source, language);
-    const file = await this._serialize(target);
-    this._logger.info(`${this._timestamp()}: Created ${file}`);
+    const target = new TranslationTarget(this.source, this._filenameFactory(language), language);
+    await this._serializer.serializeTarget(target, this._options);
+    this._logger.info(`${this._timestamp()}: Created ${target.file}`);
     this._targets.set(language, target);
     return target;
   }
@@ -61,34 +68,10 @@ export class TranslationContext {
 
     existingUnit.target = unit.target;
     existingUnit.state = unit.state;
-    this._scheduleSerialization(language);
+    this._serializeScheduler.schedule(language);
     return existingUnit;
   }
 
-  private _scheduleSerialization(language: string) {
-    const subject = this._serializeScheduler.get(language) || this._createScheduler(language);
-    subject.next();
-  }
-
-  private _createScheduler(language: string) {
-    const subject = new Subject<void>();
-    subject
-      .pipe(
-        debounceTime(500),
-        map(() => this._targets.get(language)!),
-        switchMap(t => this._serialize(t))
-      )
-      .subscribe(f => this._logger.info(`${this._timestamp()}: Updated ${f}`));
-    this._serializeScheduler.set(language, subject);
-    return subject;
-  }
-
-  private async _serialize(target: TranslationTarget) {
-    const file = this._filenameFactory(target);
-    await this._serializer.serializeTarget(file, target, this._options);
-    return file;
-  }
-
   private _timestamp() {
     const now = new Date();
     const pad = (value: number) => value.toString().padStart(2, '0');
diff --git a/builders/t9n/translation/translation-factory-configuration.ts b/builders/t9n/translation/translation-factory-configuration.ts
index 034e43c..0677570 100644
--- a/builders/t9n/translation/translation-factory-configuration.ts
+++ b/builders/t9n/translation/translation-factory-configuration.ts
@@ -2,9 +2,10 @@ import { logging } from '@angular-devkit/core';
 
 export interface TranslationFactoryConfiguration {
   logger: logging.LoggerApi;
-  source: string;
+  sourceFile: string;
   targetPath: string;
   targets: string[];
   includeContextInTarget: boolean;
   encoding: string;
+  project: string;
 }
diff --git a/builders/t9n/translation/translation-factory.ts b/builders/t9n/translation/translation-factory.ts
index 18c8e9c..923647c 100644
--- a/builders/t9n/translation/translation-factory.ts
+++ b/builders/t9n/translation/translation-factory.ts
@@ -15,7 +15,7 @@ const readFileAsync = promisify(readFile);
 
 export class TranslationFactory {
   static async createTranslationContext(configuration: TranslationFactoryConfiguration) {
-    const xlfContent = await readFileAsync(configuration.source, configuration.encoding);
+    const xlfContent = await readFileAsync(configuration.sourceFile, configuration.encoding);
     const doc = new DOMParser().parseFromString(xlfContent);
     const version = doc.documentElement.getAttribute('version');
     if (doc.documentElement.tagName !== 'xliff') {
@@ -34,71 +34,46 @@ export class TranslationFactory {
     deserializer: TranslationDeserializer,
     serializer: TranslationSerializer
   ) {
-    const { sourceLanguage, original, unitMap } = await deserializer.deserializeSource(
-      configuration.source,
+    const { language, original, unitMap } = await deserializer.deserializeSource(
+      configuration.sourceFile,
       configuration.encoding
     );
-    const source = new TranslationSource(sourceLanguage, unitMap);
-    const deserializedTargets = await Promise.all(
+    const source = new TranslationSource(configuration.sourceFile, language, unitMap);
+    const filenameFactory = this._createFilenameFactory(configuration);
+    const targets = await Promise.all(
       configuration.targets.map(target =>
-        deserializer
-          .deserializeTarget(target, configuration.encoding)
-          .then(t => new TranslationTarget(source, t.targetLanguage, t.unitMap))
+        deserializer.deserializeTarget(target, configuration.encoding)
       )
-    );
-    const targets = deserializedTargets.reduce(
-      (map, t) => map.set(t.language, t),
-      new Map<string, TranslationTarget>()
+    ).then(deserializedTargets =>
+      deserializedTargets
+        .map(t => new TranslationTarget(source, filenameFactory(t.language), t.language, t.unitMap))
+        .reduce((map, t) => map.set(t.language, t), new Map<string, TranslationTarget>())
     );
 
     const contextConfiguration: TranslationContextConfiguration = {
-      encoding: configuration.encoding,
-      includeContextInTarget: configuration.includeContextInTarget,
-      filenameFactory: this._createFilenameFactory(configuration.source, configuration.targetPath),
-      original,
-      serializer,
+      ...configuration,
       source,
-      targets
+      targets,
+      filenameFactory,
+      original,
+      serializer
     };
 
-    await this._migrateSourceToTargetLanguage(contextConfiguration);
-    return new TranslationContext(configuration.logger, contextConfiguration);
+    const context = new TranslationContext(contextConfiguration);
+    const sourceTarget =
+      context.target(source.language) || (await context.createTarget(source.language));
+    sourceTarget.units.forEach(u => Object.assign(u, { target: u.source, state: 'final' }));
+    await serializer.serializeTarget(sourceTarget, contextConfiguration);
+    return context;
   }
 
-  private static _createFilenameFactory(
-    source: string,
-    targetPath: string
-  ): (target: TranslationTarget) => string {
-    const extension = extname(source);
-    const filename = basename(source);
+  private static _createFilenameFactory(configuration: {
+    sourceFile: string;
+    targetPath: string;
+  }): (language: string) => string {
+    const extension = extname(configuration.sourceFile);
+    const filename = basename(configuration.sourceFile);
     const namePart = filename.substring(0, filename.length - extension.length);
-    return t => join(targetPath, `${namePart}.${t.language}${extension}`);
-  }
-
-  private static async _migrateSourceToTargetLanguage({
-    encoding,
-    includeContextInTarget,
-    filenameFactory,
-    original,
-    source,
-    targets,
-    serializer
-  }: TranslationContextConfiguration) {
-    let target = targets.get(source.language);
-    if (!target) {
-      target = new TranslationTarget(source, source.language);
-      targets.set(source.language, target);
-    }
-
-    target.units.forEach(u => {
-      u.target = u.source;
-      u.state = 'final';
-    });
-
-    await serializer.serializeTarget(filenameFactory(target), target, {
-      original,
-      encoding,
-      includeContextInTarget
-    });
+    return l => join(configuration.targetPath, `${namePart}.${l}${extension}`);
   }
 }
diff --git a/builders/t9n/translation/translation-source.ts b/builders/t9n/translation/translation-source.ts
index f2a8172..c804106 100644
--- a/builders/t9n/translation/translation-source.ts
+++ b/builders/t9n/translation/translation-source.ts
@@ -3,7 +3,11 @@ import { TranslationSourceUnit } from './translation-source-unit';
 export class TranslationSource {
   readonly units: TranslationSourceUnit[];
 
-  constructor(readonly language: string, readonly unitMap: Map<string, TranslationSourceUnit>) {
+  constructor(
+    readonly file: string,
+    readonly language: string,
+    readonly unitMap: Map<string, TranslationSourceUnit>
+  ) {
     this.units = Array.from(this.unitMap.values());
   }
 }
diff --git a/builders/t9n/translation/translation-target.ts b/builders/t9n/translation/translation-target.ts
index e472679..bec8f2a 100644
--- a/builders/t9n/translation/translation-target.ts
+++ b/builders/t9n/translation/translation-target.ts
@@ -11,6 +11,7 @@ export class TranslationTarget {
 
   constructor(
     readonly source: TranslationSource,
+    readonly file: string,
     readonly language: string,
     unitMap = new Map<string, TranslationTargetUnit>()
   ) {