[JAVA][library: vertx] generated client does not maintain backwards compatibility with older versions of vertx

Created by: ccozzolino

Description

The buildResponseHandler method defined in Java/libraries/vertx/ApiClient.mustache makes a call to Json.decodeValue(String, Class<T>) which is not supported in older versions (< 3.5) of Vert.x. The call should be adjusted to handle all versions.

Swagger-codegen version

All versions with vertx async & rx support

Suggest a fix/enhancement

Change the call from:

resultContent = Json.decodeValue(httpResponse.body(), returnType);

to:

try {
   resultContent = Json.mapper.readValue(httpResponse.bodyAsString(), returnType);
} catch (Exception e) {
   throw new DecodeException("Failed to decode:" + e.getMessage(), e);
}