JAX-RS: java.util.Optional is an unrecognized type

[schmitzhermes]

Hey folks,
I am using dropwizard in connection with Swagger (no Bundle or anything, just Swagger as a plain JAX-RS resource). I played around with java.util.Optional query params a bit. That works fine, but swagger seems to have a problem with Optional.

java.lang.IllegalArgumentException: Unrecognized Type: [null]
	at com.fasterxml.jackson.databind.type.TypeFactory._fromAny(TypeFactory.java:1170)
	at com.fasterxml.jackson.databind.type.TypeFactory.constructType(TypeFactory.java:618)
	at com.fasterxml.jackson.databind.ObjectMapper.constructType(ObjectMapper.java:1543)
	at io.swagger.jackson.ModelResolver.resolveProperty(ModelResolver.java:110)
	at io.swagger.converter.ModelConverterContextImpl.resolveProperty(ModelConverterContextImpl.java:80)
	at io.swagger.jackson.ModelResolver.resolveProperty(ModelResolver.java:156)
	at io.swagger.jackson.ModelResolver.resolveProperty(ModelResolver.java:110)
	at io.swagger.converter.ModelConverterContextImpl.resolveProperty(ModelConverterContextImpl.java:80)
	at io.swagger.converter.ModelConverters.readAsProperty(ModelConverters.java:58)
	at io.swagger.jaxrs.DefaultParameterExtension.createProperty(DefaultParameterExtension.java:204)
	at io.swagger.jaxrs.DefaultParameterExtension.extractParameters(DefaultParameterExtension.java:66)
	at io.swagger.jaxrs.ext.AbstractSwaggerExtension.extractParameters(AbstractSwaggerExtension.java:33)
	at io.swagger.jersey.SwaggerJersey2Jaxrs.extractParameters(SwaggerJersey2Jaxrs.java:63)
	at io.swagger.jaxrs.DefaultParameterExtension.handleAdditionalAnnotation(DefaultParameterExtension.java:185)
	at io.swagger.jaxrs.DefaultParameterExtension.extractParameters(DefaultParameterExtension.java:108)
	at io.swagger.jaxrs.ext.AbstractSwaggerExtension.extractParameters(AbstractSwaggerExtension.java:33)
	at io.swagger.jersey.SwaggerJersey2Jaxrs.extractParameters(SwaggerJersey2Jaxrs.java:63)
	at io.swagger.jaxrs.Reader.getParameters(Reader.java:1035)
	at io.swagger.jaxrs.Reader.parseMethod(Reader.java:974)
	at io.swagger.jaxrs.Reader.read(Reader.java:322)
	at io.swagger.jaxrs.Reader.read(Reader.java:172)
	at io.swagger.jaxrs.config.BeanConfig.scanAndRead(BeanConfig.java:242)
	at io.swagger.jaxrs.config.BeanConfig.setScan(BeanConfig.java:221)
	[...]
	at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:43)
	at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:85)
	at io.dropwizard.testing.DropwizardTestSupport.startIfRequired(DropwizardTestSupport.java:194)
	at io.dropwizard.testing.DropwizardTestSupport.before(DropwizardTestSupport.java:112)
	at io.dropwizard.testing.junit.DropwizardAppRule.before(DropwizardAppRule.java:128)
	at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:46)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

This issue is caused because propType.containedType(0) resolves to null (find the source here). I also tried to add jackson in version 2.8.7 manually to the classpath, but it didn't help.

I already found a couple of issues regarding swagger and Optional, but they were all stating that this issue is resolved. Can you guys provide any help?

I'd be glad to help you out with further information.

[pjfanning]

Have you tried registering the Jackson Java8 module(s)?

io.swagger.util.Json.mapper().registerModule(new Jdk8Module())