We've just updated the Groovy client generator to support the latest version of Groovy (2.5.7). To generate a Groovy API client given an OpenAPI spec, please follow the steps below:

1. Download the Java JAR (https://oss.sonatype.org/content/repositories/snapshots/org/...)

2. Rename the JAR as "openapi-generator-cli.jar"

3. Run the following command to generate a Groovy API client for the Petstore API (https://raw.githubusercontent.com/OpenAPITools/openapi-gener...):

Mac/Linux:

- java -jar openapi-generator-cli.jar generate -g groovy -i https://raw.githubusercontent.com/OpenAPITools/openapi-gener... -o /var/tmp/groovy-api-client/

Windows:

- java -jar openapi-generator-cli.jar generate -g groovy -i https://raw.githubusercontent.com/OpenAPITools/openapi-gener... -o C:\tmp\groovy-api-client

Thanks Vincent Devos for his contribution on this (https://github.com/OpenAPITools/openapi-generator/pull/2847)

Best regards,

William