Fix the bug of getting the number of threads

hippo4j-common/src/main/java/cn/hippo4j/common/model/ThreadPoolParameterInfo.java

@@ -118,6 +118,6 @@ public class ThreadPoolParameterInfo implements ThreadPoolParameter, Serializabl
     }
 
     public Integer getMaximumPoolSize() {
-        return this.maximumPoolSize == null ? this.maxSize : this.corePoolSize;
+        return this.maximumPoolSize == null ? this.maxSize : this.maximumPoolSize;
     }
 }