Improve null-safety of module/spring-boot-graphql

See spring-projectsgh-46926

Author: mhalbritter

module/spring-boot-graphql/src/main/java/org/springframework/boot/graphql/autoconfigure/reactive/GraphQlWebFluxAutoConfiguration.java

@@ -59,6 +59,7 @@
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.codec.ServerCodecConfigurer;
+import org.springframework.util.Assert;
 import org.springframework.web.cors.CorsConfiguration;
 import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.config.CorsRegistry;
@@ -190,6 +191,7 @@ GraphQlWebSocketHandler graphQlWebSocketHandler(WebGraphQlHandler webGraphQlHand
 		HandlerMapping graphQlWebSocketEndpoint(GraphQlWebSocketHandler graphQlWebSocketHandler,
 				GraphQlProperties properties) {
 			String path = properties.getWebsocket().getPath();
+			Assert.state(path != null, "'path' must not be null");
 			logger.info(LogMessage.format("GraphQL endpoint WebSocket %s", path));
 			SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
 			mapping.setHandlerPredicate(new WebSocketUpgradeHandlerPredicate());

module/spring-boot-graphql/src/main/java/org/springframework/boot/graphql/autoconfigure/servlet/GraphQlWebMvcAutoConfiguration.java

@@ -62,6 +62,7 @@
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.GenericHttpMessageConverter;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.util.Assert;
 import org.springframework.web.cors.CorsConfiguration;
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.config.annotation.CorsRegistry;
@@ -212,6 +213,7 @@ private GenericHttpMessageConverter<Object> asGenericHttpMessageConverter(HttpMe
 		@Bean
 		HandlerMapping graphQlWebSocketMapping(GraphQlWebSocketHandler handler, GraphQlProperties properties) {
 			String path = properties.getWebsocket().getPath();
+			Assert.state(path != null, "'path' must not be null");
 			logger.info(LogMessage.format("GraphQL endpoint WebSocket %s", path));
 			WebSocketHandlerMapping mapping = new WebSocketHandlerMapping();
 			mapping.setWebSocketUpgradeMatch(true);