Remove unfavourable usage of classes

ee/app/assets/javascripts/vue_shared/license_management/mappers/v1.js

-/* eslint-disable class-methods-use-this */
-
-export default class {
-  mapFrom(report) {
-    return report;
-  }
-}

ee/app/assets/javascripts/vue_shared/license_management/mappers/v2.js

-import { byLicenseNameComparator } from '../store/utils';
-
-export default class V2 {
-  mapFrom(report) {
-    this.licenseMap = V2.createLicenseMap(report.licenses);
-    this.licenses = report.licenses.sort(byLicenseNameComparator).map(V2.mapFromLicense);
-
-    return {
-      licenses: this.licenses,
-      dependencies: report.dependencies.map(v2Dependency => this.mapFromDependency(v2Dependency)),
-    };
-  }
-
-  combine(licenses) {
-    return licenses.reduce(
-      (memo, licenseId) => {
-        const license = this.licenseMap[licenseId];
-        this.incrementCountFor(license.name);
-
-        if (memo.name === null) {
-          return {
-            name: license.name,
-            url: license.url,
-          };
-        }
-        return { name: `${memo.name}, ${license.name}`, url: '' };
-      },
-      { name: null, url: null },
-    );
-  }
-
-  incrementCountFor(licenseName) {
-    const legacyLicense = this.licenses.find(license => license.name === licenseName);
-    if (legacyLicense) legacyLicense.count += 1;
-  }
-
-  mapFromDependency(dependency) {
-    return {
-      license: this.combine(dependency.licenses),
-      dependency: {
-        name: dependency.name,
-        url: dependency.url,
-        description: dependency.description,
-      },
-    };
-  }
-
-  static mapFromLicense(license) {
-    return { name: license.name, count: 0 };
-  }
-
-  static createLicenseMap(licenses) {
-    return licenses.reduce((memo, item) => {
-      memo[item.id] = { name: item.name, url: item.url }; // eslint-disable-line no-param-reassign
-      return memo;
-    }, {});
-  }
-}

ee/app/assets/javascripts/vue_shared/license_management/report_mapper.js

-import V1 from './mappers/v1';
-import V2 from './mappers/v2';
+import { byLicenseNameComparator } from './store/utils';
+
+class V2ToV1Mapper {
+  mapFrom(report) {
+    this.licenseMap = V2ToV1Mapper.createLicenseMap(report.licenses);
+    this.licenses = report.licenses.sort(byLicenseNameComparator).map(V2ToV1Mapper.mapFromLicense);
+
+    return {
+      licenses: this.licenses,
+      dependencies: report.dependencies.map(v2Dependency => this.mapFromDependency(v2Dependency)),
+    };
+  }
+
+  combine(licenses) {
+    return licenses.reduce(
+      (memo, licenseId) => {
+        const license = this.licenseMap[licenseId];
+        this.incrementCountFor(license.name);
+
+        if (memo.name === null) {
+          return {
+            name: license.name,
+            url: license.url,
+          };
+        }
+        return { name: `${memo.name}, ${license.name}`, url: '' };
+      },
+      { name: null, url: null },
+    );
+  }
+
+  incrementCountFor(licenseName) {
+    const legacyLicense = this.licenses.find(license => license.name === licenseName);
+    if (legacyLicense) legacyLicense.count += 1;
+  }
+
+  mapFromDependency(dependency) {
+    return {
+      license: this.combine(dependency.licenses),
+      dependency: {
+        name: dependency.name,
+        url: dependency.url,
+        description: dependency.description,
+      },
+    };
+  }
+
+  static mapFromLicense(license) {
+    return { name: license.name, count: 0 };
+  }
+
+  static createLicenseMap(licenses) {
+    return licenses.reduce((memo, item) => {
+      memo[item.id] = { name: item.name, url: item.url }; // eslint-disable-line no-param-reassign
+      return memo;
+    }, {});
+  }
+}
+
+const DEFAULT_VERSION = '1';
 
 export default class ReportMapper {
   constructor() {
-    this.mappers = { '1': V1, '2': V2 };
+    this.mappers = {
+      '1': report => report,
+      '2': report => new V2ToV1Mapper().mapFrom(report),
+    };
   }
 
   mapFrom(reportArtifact) {
     const majorVersion = ReportMapper.majorVersion(reportArtifact);
-    return this.mapperFor(majorVersion).mapFrom(reportArtifact);
+    return this.mapperFor(majorVersion)(reportArtifact);
   }
 
   mapperFor(majorVersion) {
-    return new this.mappers[majorVersion]();
+    return this.mappers[majorVersion];
   }
 
   static majorVersion(report) {
-    return report && report.version ? report.version.split('.')[0] : '1';
+    return report && report.version ? report.version.split('.')[0] : DEFAULT_VERSION;
   }
 }