Call remove() on ThreadLocal in SpringBootMockMvcBuilderCustomizer

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/web/servlet/SpringBootMockMvcBuilderCustomizer.java

@@ -253,7 +253,7 @@ public class SpringBootMockMvcBuilderCustomizer implements MockMvcBuilderCustomi
 		}
 
 		void clear() {
-			this.lines.get().clear();
+			this.lines.remove();
 		}
 
 	}