dagger.internal.codegen.Util$CodeGenerationIncompleteException: Unknown type r eturned as <error>

[zakiravian]

Hey Guys,
We are facing problem while compiling our code using dagger 1.2.1. Can you please guide us how to resolve the issue. I am copying full stacktrace below. Your urgent help will be highly appreciated. Thanks.
provided 'com.squareup.dagger:dagger-compiler:1.2.1'

:app:mergeReleaseResources
:app:processReleaseManifest
:app:processReleaseResources
:app:generateReleaseSources
:app:compileReleaseJavaWithJavac FAILED

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':app:compileReleaseJavaWithJavac'.

  dagger.internal.codegen.Util$CodeGenerationIncompleteException: Unknown type r
  eturned as .

• Try:
  Run with --info or --debug option to get more log output.

• Exception is:
  org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:com
  pileReleaseJavaWithJavac'.
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
  ecuteActions(ExecuteActionsTaskExecuter.java:69)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
  ecute(ExecuteActionsTaskExecuter.java:46)
  at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExec
  uter.execute(PostExecutionAnalysisTaskExecuter.java:35)
  at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.exec
  ute(SkipUpToDateTaskExecuter.java:64)
  at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execut
  e(ValidatingTaskExecuter.java:58)
  at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecu
  ter.execute(SkipEmptySourceFilesTaskExecuter.java:52)
  at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter
  .execute(SkipTaskWithNoActionsExecuter.java:52)
  at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execut
  e(SkipOnlyIfTaskExecuter.java:53)
  at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter
  .execute(ExecuteAtMostOnceTaskExecuter.java:43)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTa
  skWorker.execute(DefaultTaskGraphExecuter.java:203)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTa
  skWorker.execute(DefaultTaskGraphExecuter.java:185)
  at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorW
  orker.processTask(AbstractTaskPlanExecutor.java:62)
  at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorW
  orker.run(AbstractTaskPlanExecutor.java:50)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(Defaul
  tTaskPlanExecutor.java:25)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(Defau
  ltTaskGraphExecuter.java:110)
  at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTask
  ExecutionAction.java:37)
  at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
  r.java:37)
  at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExec
  uter.java:23)
  at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecu
  ter.java:43)
  at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildEx
  ecutionAction.java:32)
  at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
  r.java:37)
  at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
  r.java:30)
  at org.gradle.initialization.DefaultGradleLauncher$4.run(DefaultGradleLa
  uncher.java:154)
  at org.gradle.internal.Factories$1.create(Factories.java:22)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(Defaul
  tBuildOperationExecutor.java:90)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(Defaul
  tBuildOperationExecutor.java:52)
  at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(Default
  GradleLauncher.java:151)
  at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGra
  dleLauncher.java:32)
  at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradl
  eLauncher.java:99)
  at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradl
  eLauncher.java:93)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(Defaul
  tBuildOperationExecutor.java:90)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(Defaul
  tBuildOperationExecutor.java:62)
  at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradle
  Launcher.java:93)
  at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLaun
  cher.java:82)
  at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildCon
  troller.run(InProcessBuildActionExecuter.java:94)
  at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(Exe
  cuteBuildActionRunner.java:28)
  at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildA
  ctionRunner.java:35)
  at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProce
  ssBuildActionExecuter.java:43)
  at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProce
  ssBuildActionExecuter.java:28)
  at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(Contin
  uousBuildActionExecuter.java:77)
  at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(Contin
  uousBuildActionExecuter.java:47)
  at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.exe
  cute(DaemonUsageSuggestingBuildActionExecuter.java:51)
  at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.exe
  cute(DaemonUsageSuggestingBuildActionExecuter.java:28)
  at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:43)
  at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.jav
  a:170)
  at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.
  execute(CommandLineActionFactory.java:237)
  at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.
  execute(CommandLineActionFactory.java:210)
  at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRunti
  meValidationAction.java:35)
  at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRunti
  meValidationAction.java:24)
  at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(
  CommandLineActionFactory.java:206)
  at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(
  CommandLineActionFactory.java:169)
  at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionRep
  ortingAction.java:33)
  at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionRep
  ortingAction.java:22)
  at org.gradle.launcher.Main.doAction(Main.java:33)
  at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
  at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBoots
  trap.java:54)
  at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.j
  ava:35)
  at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
  at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.ja
  va:30)
  at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:129)
  at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
  Caused by: java.lang.RuntimeException: dagger.internal.codegen.Util$CodeGenerati
  onIncompleteException: Unknown type returned as .
  at com.sun.tools.javac.main.Main.compile(Main.java:469)
  at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:132)
  at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJava
  Compiler.java:45)
  at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJava
  Compiler.java:33)
  at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegat
  eAndHandleErrors(NormalizingJavaCompiler.java:101)
  at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute
  (NormalizingJavaCompiler.java:50)
  at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute
  (NormalizingJavaCompiler.java:36)
  at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.exe
  cute(CleaningJavaCompilerSupport.java:34)
  at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.exe
  cute(CleaningJavaCompilerSupport.java:25)
  at org.gradle.api.tasks.compile.JavaCompile.performCompilation(JavaCompi
  le.java:157)
  at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:139
  )
  at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:93)

  at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
  at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
  

  actory$IncrementalTaskAction.doExecute(AnnotationProcessingTaskFactory.java:244)

  at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
  

  actory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:220)
  at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
  actory$IncrementalTaskAction.execute(AnnotationProcessingTaskFactory.java:231)
  at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
  actory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:209)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
  ecuteAction(ExecuteActionsTaskExecuter.java:80)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
  ecuteActions(ExecuteActionsTaskExecuter.java:61)
  ... 60 more
  Caused by: dagger.internal.codegen.Util$CodeGenerationIncompleteException: Unkno
  wn type returned as .
  at dagger.internal.codegen.Util$2.visitString(Util.java:164)
  at dagger.internal.codegen.Util$2.visitString(Util.java:161)
  at com.sun.tools.javac.code.Attribute$Error.accept(Attribute.java:269)
  at dagger.internal.codegen.Util$2.visitArray(Util.java:179)
  at dagger.internal.codegen.Util$2.visitArray(Util.java:161)
  at com.sun.tools.javac.code.Attribute$Array.accept(Attribute.java:233)
  at dagger.internal.codegen.Util.getAnnotation(Util.java:205)
  at dagger.internal.codegen.GraphAnalysisProcessor.collectIncludesRecursi
  vely(GraphAnalysisProcessor.java:283)
  at dagger.internal.codegen.GraphAnalysisProcessor.collectIncludesRecursi
  vely(GraphAnalysisProcessor.java:324)
  at dagger.internal.codegen.GraphAnalysisProcessor.processCompleteModule(
  GraphAnalysisProcessor.java:166)
  at dagger.internal.codegen.GraphAnalysisProcessor.process(GraphAnalysisP
  rocessor.java:148)
  at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcess
  or(JavacProcessingEnvironment.java:793)
  at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$200(
  JavacProcessingEnvironment.java:97)
  at com.sun.tools.javac.processing.JavacProcessingEnvironment$DiscoveredP
  rocessors$ProcessorStateIterator.runContributingProcs(JavacProcessingEnvironment
  .java:644)
  at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(J
  avacProcessingEnvironment.java:1027)
  at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessin
  g(JavacProcessingEnvironment.java:1185)
  at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler
  .java:1108)
  at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:824)
  at com.sun.tools.javac.main.Main.compile(Main.java:439)
  ... 78 more

BUILD FAILED