use MethodParameter#isOptional() instead of checking for Optional type

Check for whether a parameter is required now uses isOptional()
method. This improves integration with JSR-305 annotations
and Kotlin nullability.

Author: Marcin Zarebski

springdoc-openapi-common/src/main/java/org/springdoc/core/AbstractRequestBuilder.java

@@ -279,8 +279,7 @@ private Parameter buildParams(ParameterInfo parameterInfo, Components components
 
 		}
 		else if (requestParam != null && !parameterBuilder.isFile(parameterInfo.getParameter())) {
-			boolean isOptional = Optional.class.equals(methodParameter.getParameterType());
-			requestInfo = new RequestInfo(ParameterIn.QUERY.toString(), requestParam.value(), requestParam.required() && !isOptional,
+			requestInfo = new RequestInfo(ParameterIn.QUERY.toString(), requestParam.value(), requestParam.required() && !methodParameter.isOptional(),
 					requestParam.defaultValue());
 			parameter = buildParam(parameterInfo, components, requestInfo, jsonView);
 		}