Maven clean install problem

Hi I cloned the repo with sources, and typed `maven clean install` in root folder. That is my error output:

```bash
$ mvn clean install -e
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] Computing target platform for MavenProject: com.gwtplugins.eclipse:com.gwtplugins.eclipse.suite.v3.feature:3.0.0-SNAPSHOT @ F:\AnotherProjects\gwt-eclipse-plugin\features\com.gwtplugins.eclipse.suite.v3.feature\pom.xml
[INFO] Adding repository http://download.eclipse.org/cbi/updates/license
[ERROR] Failed to resolve target definition F:\AnotherProjects\gwt-eclipse-plugin\eclipse\mars\gwt-eclipse-mars.target: Failed to load p2 metadata repository from location http://download.eclipse.org/cbi/updates/license: HTTP Proxy Authentication Required: http://download.eclipse.org/cbi/updates/license/content.xml -> [Help 1]
org.apache.maven.MavenExecutionException: Failed to resolve target definition F:\AnotherProjects\gwt-eclipse-plugin\eclipse\mars\gwt-eclipse-mars.target: Failed to load p2 metadata repository from location http://download.eclipse.org/cbi/updates/license
at org.eclipse.tycho.core.maven.TychoMavenLifecycleParticipant.afterProjectsRead(TychoMavenLifecycleParticipant.java:100)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:266)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.eclipse.tycho.core.shared.BuildFailureException: Failed to resolve target definition F:\AnotherProjects\gwt-eclipse-plugin\eclipse\mars\gwt-eclipse-mars.target: Failed to load p2 metadata repository from location http://download.eclipse.org/cbi/updates/license
at org.eclipse.tycho.p2.target.TargetDefinitionResolver.resolveContent(TargetDefinitionResolver.java:99)
at org.eclipse.tycho.p2.target.TargetDefinitionResolverService.resolveFromArguments(TargetDefinitionResolverService.java:70)
at org.eclipse.tycho.p2.target.TargetDefinitionResolverService.getTargetDefinitionContent(TargetDefinitionResolverService.java:60)
at org.eclipse.tycho.p2.target.TargetPlatformFactoryImpl.resolveTargetDefinitions(TargetPlatformFactoryImpl.java:214)
at org.eclipse.tycho.p2.target.TargetPlatformFactoryImpl.createTargetPlatform(TargetPlatformFactoryImpl.java:155)
at org.eclipse.tycho.p2.target.TargetPlatformFactoryImpl.createTargetPlatform(TargetPlatformFactoryImpl.java:128)
at org.eclipse.tycho.p2.target.TargetPlatformFactoryImpl.createTargetPlatform(TargetPlatformFactoryImpl.java:1)
at org.eclipse.tycho.p2.manager.ReactorRepositoryManagerImpl.computePreliminaryTargetPlatform(ReactorRepositoryManagerImpl.java:84)
at org.eclipse.tycho.p2.resolver.P2DependencyResolver.computePreliminaryTargetPlatform(P2DependencyResolver.java:223)
at org.eclipse.tycho.core.resolver.DefaultTychoResolver.resolveProject(DefaultTychoResolver.java:109)
at org.eclipse.tycho.core.maven.TychoMavenLifecycleParticipant.afterProjectsRead(TychoMavenLifecycleParticipant.java:95)
... 14 more
Caused by: org.eclipse.tycho.p2.target.facade.TargetDefinitionResolutionException: Failed to load p2 metadata repository from location http://download.eclipse.org/cbi/updates/license
at org.eclipse.tycho.p2.target.TargetDefinitionResolver$LoadedIULocation.loadRepository(TargetDefinitionResolver.java:290)
at org.eclipse.tycho.p2.target.TargetDefinitionResolver$LoadedIULocation.(TargetDefinitionResolver.java:282)
at org.eclipse.tycho.p2.target.TargetDefinitionResolver$ResolverRun.addLocation(TargetDefinitionResolver.java:154)
at org.eclipse.tycho.p2.target.TargetDefinitionResolver.resolveContentWithExceptions(TargetDefinitionResolver.java:121)
at org.eclipse.tycho.p2.target.TargetDefinitionResolver.resolveContent(TargetDefinitionResolver.java:94)
... 24 more
Caused by: org.eclipse.equinox.p2.core.ProvisionException: HTTP Proxy Authentication Required: http://download.eclipse.org/cbi/updates/license/content.xml
at org.eclipse.equinox.internal.p2.repository.CacheManager.createCache(CacheManager.java:243)
at org.eclipse.tycho.p2.remote.RemoteRepositoryCacheManager.createCache(RemoteRepositoryCacheManager.java:67)
at org.eclipse.equinox.internal.p2.metadata.repository.SimpleMetadataRepositoryFactory.getLocalFile(SimpleMetadataRepositoryFactory.java:66)
at org.eclipse.equinox.internal.p2.metadata.repository.SimpleMetadataRepositoryFactory.load(SimpleMetadataRepositoryFactory.java:88)
at org.eclipse.equinox.internal.p2.metadata.repository.MetadataRepositoryManager.factoryLoad(MetadataRepositoryManager.java:57)
at org.eclipse.equinox.internal.p2.repository.helpers.AbstractRepositoryManager.loadRepository(AbstractRepositoryManager.java:768)
at org.eclipse.equinox.internal.p2.repository.helpers.AbstractRepositoryManager.loadRepository(AbstractRepositoryManager.java:668)
at org.eclipse.equinox.internal.p2.metadata.repository.MetadataRepositoryManager.loadRepository(MetadataRepositoryManager.java:96)
at org.eclipse.tycho.p2.remote.RemoteMetadataRepositoryManager.loadRepository(RemoteMetadataRepositoryManager.java:61)
at org.eclipse.tycho.p2.remote.RemoteMetadataRepositoryManager.loadRepository(RemoteMetadataRepositoryManager.java:53)
at org.eclipse.tycho.p2.target.TargetDefinitionResolver$LoadedIULocation.loadRepository(TargetDefinitionResolver.java:288)
... 28 more
Caused by: org.eclipse.ecf.filetransfer.BrowseFileTransferException: Proxy Authentication Required
at org.eclipse.ecf.provider.filetransfer.httpclient4.HttpClientFileSystemBrowser.runRequest(HttpClientFileSystemBrowser.java:291)
at org.eclipse.ecf.provider.filetransfer.browse.AbstractFileSystemBrowser$DirectoryJob.run(AbstractFileSystemBrowser.java:69)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MavenExecutionException

```

Tái hiện lệnh `mvn clean install` trong thư mục gốc và kiểm tra `eclipse/mars/gwt-eclipse-mars.target`, đặc biệt là location `http://download.eclipse.org/cbi/updates/license` của nó. Xác định xem lỗi có đặc thù với việc xác thực proxy hay với cấu hình dự án, và ghi lại kết quả build có thể tái hiện.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.