in geronimo-openapi-impl/src/main/java/org/apache/geronimo/microprofile/openapi/impl/model/ExtensibleImpl.java [40:47]
public T addExtension(final String key, final Object _extensions) {
if (_extensions == null) {
return (T) this;
}
(this._extensions = this._extensions == null ? new LinkedHashMap<>() : this._extensions)
.put((key.startsWith("x-") ? key : ("x-" + key)), _extensions);
return (T) this;
}