Historically Java was able to handle the biggest enterprise problem(s) with its Write once,run anywhere(WORA) paradigm. With Cloud Native Applications grown to popularity, things like running applications as linux containers, serverless taking centre stage -- Java was pushed back by languages like golang, node.js as the forerunner to build Cloud Native Applications as they are smaller, quicker and arguably more nimble.
The OpenAPI Specification (formally known as Swagger) describes APIs in a way that is standardized, machine-readable, and programming language-agnostic. It is an open source project hosted by the Linux Foundation.
There have been many announcements regarding frameworks or tools supporting this standard: For example, Eclipse MicroProfile 1.3 provides a set of annotations that can be used on top of JAX-RS, and version 3.5.2 of Eclipse Vert.x provides automatic requests validation.