NPE in ExampleJsonGenerator

[hirth-abi]

Describe the bug

The ExampleJsonGenerator for objects always expects that the schema has non-null properties. This if often not the case, for example if a schema refers to another one, only the name and the $ref properties are set, all others, especially properties are null.

Dependencies and versions used

Springwolf 0.13.0

Code example

springwolf-core/springwolf-core/src/main/java/io/github/stavshamir/springwolf/schemas/example/ExampleJsonGenerator.java

Line 134 in 7b9c709

String data = properties.entrySet().stream()

Stack trace and error logs

Caused by: java.lang.RuntimeException: Error occured during creation of AsyncAPI
	at io.github.stavshamir.springwolf.asyncapi.DefaultAsyncApiService.getAsyncAPI(DefaultAsyncApiService.java:45)
	at io.github.stavshamir.springwolf.asyncapi.SpringwolfInitApplicationListener.afterPropertiesSet(SpringwolfInitApplicationListener.java:39)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1817)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1766)
	... 16 common frames omitted
Caused by: java.lang.NullPointerException: Cannot invoke "java.util.Map.entrySet()" because "properties" is null
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.handleObject(ExampleJsonGenerator.java:134)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:69)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.handleArraySchema(ExampleJsonGenerator.java:92)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:65)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.lambda$handleObject$0(ExampleJsonGenerator.java:140)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1845)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.handleObject(ExampleJsonGenerator.java:144)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:69)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:61)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.lambda$handleObject$0(ExampleJsonGenerator.java:140)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1845)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.handleObject(ExampleJsonGenerator.java:144)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:69)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:61)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.lambda$handleObject$0(ExampleJsonGenerator.java:140)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1845)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.handleObject(ExampleJsonGenerator.java:144)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.buildSchema(ExampleJsonGenerator.java:69)
	at io.github.stavshamir.springwolf.schemas.example.ExampleJsonGenerator.fromSchema(ExampleJsonGenerator.java:39)
	at io.github.stavshamir.springwolf.schemas.DefaultSchemasService.generateExampleWhenMissing(DefaultSchemasService.java:89)
	at java.base/java.util.HashMap.forEach(HashMap.java:1421)
	at io.github.stavshamir.springwolf.schemas.DefaultSchemasService.finalizeDefinitions(DefaultSchemasService.java:45)
	at io.github.stavshamir.springwolf.schemas.DefaultSchemasService.getDefinitions(DefaultSchemasService.java:39)
	at io.github.stavshamir.springwolf.asyncapi.DefaultAsyncApiService.initAsyncAPI(DefaultAsyncApiService.java:71)
	at io.github.stavshamir.springwolf.asyncapi.DefaultAsyncApiService.getAsyncAPI(DefaultAsyncApiService.java:39)
	... 19 common frames omitted

[timonback]

Hi @hirth-abi,

Thank you for the bug report and technical details.

I addressed the NPE in #316 and also added a more complex example to close the test gap.

Based on this report as well as #315, I suspect there are more cases. Are you able to replicate/contribute a test case or provide your DTO structure? Based on the stacktrace, I am only able to see that there is an object -> object -> object -> array -> object relationship. Class and property names do not matter, feel free to have a look at the PR.
I am also happy to help and make the test green, but can only assume the class structure at this point.

[timonback]

Thank your for the report, the issue has been addressed in the new release.

Feel free to reopen this issue if there is still something missing.

Also, please participate in #342 if you can :)