StackOverflowError on DefaultCodegen.isDiscriminatorInInterfaceTree

Description

java -jar swagger-codegen-cli-2.3.1.jar generate -i bitbucket.json -l dart -o bitbucket_api -c bitbucket_pr_config.json

[main] INFO io.swagger.parser.Swagger20Parser - reading from bitbucket.json
[main] WARN io.swagger.codegen.ignore.CodegenIgnoreProcessor - Output directory does not exist, or is inaccessible. No file (.swagger-codegen-ignore) will be evaluated.
Exception in thread "main" java.lang.StackOverflowError
	at io.swagger.codegen.DefaultCodegen.isDiscriminatorInInterfaceTree(DefaultCodegen.java:1473)
	at io.swagger.codegen.DefaultCodegen.isDiscriminatorInInterfaceTree(DefaultCodegen.java:1480)
	at io.swagger.codegen.DefaultCodegen.isDiscriminatorInInterfaceTree(DefaultCodegen.java:1480)
	at io.swagger.codegen.DefaultCodegen.isDiscriminatorInInterfaceTree(DefaultCodegen.java:1480)

Swagger-codegen version

swagger-codegen-cli-2.3.1.jar
also happens with 3.0

Swagger declaration file content or url

https://bitbucket.org/api/swagger.json

Command line used for generation

java -jar swagger-codegen-cli-2.3.1.jar generate -i bitbucket.json -l dart -o bitbucket_api -c bitbucket_pr_config.json

Start in DefaultCodegen.java at isDiscriminatorInInterfaceTree, using the repeated stack trace at lines 1473 and 1480 to inspect the recursion. Reproduce with swagger-codegen-cli-2.3.1, the Bitbucket swagger.json declaration, and the supplied Dart generation command; done means generation no longer ends in StackOverflowError.