fix code

hutool-db/src/main/java/org/dromara/hutool/db/config/ConnectionConfig.java

@@ -186,4 +186,16 @@ public class ConnectionConfig<T extends ConnectionConfig<?>> {
 		this.poolProps.setProperty(key, value);
 		return (T) this;
 	}
+
+	@Override
+	public String toString() {
+		return "ConnectionConfig{" +
+			"driver='" + driver + '\'' +
+			", url='" + url + '\'' +
+			", user='" + user + '\'' +
+			", pass='****" + '\'' +
+			", connProps=" + connProps +
+			", poolProps=" + poolProps +
+			'}';
+	}
 }

hutool-db/src/main/java/org/dromara/hutool/db/ds/c3p0/C3p0DSFactory.java

@@ -56,7 +56,7 @@ public class C3p0DSFactory implements DSFactory {
 		// 连接配置
 		final Properties connProps = config.getConnProps();
 		if(MapUtil.isNotEmpty(connProps)){
-			ds.setProperties(connProps);
+			ds.getProperties().putAll(connProps);
 		}
 
 		return ds;