add some comments to persistence.xml

Author: gavinking

example/src/main/resources/META-INF/persistence.xml

@@ -9,23 +9,33 @@
         <class>org.hibernate.example.reactive.Book</class>
 
         <properties>
+
+            <!-- PostgreSQL -->
             <property name="javax.persistence.jdbc.url"
                       value="jdbc:postgresql://localhost:5432/hreact"/>
+
+            <!-- MySQL -->
             <!--property name="javax.persistence.jdbc.url"
                       value="jdbc:mysql://localhost:3306/hreact"/-->
 
+            <!-- Credentials -->
             <property name="javax.persistence.jdbc.user"
                       value="hreact"/>
             <property name="javax.persistence.jdbc.password"
                       value="hreact"/>
 
+            <!-- The Vert.x SQL Client connection pool size -->
             <property name="hibernate.connection.pool_size"
                       value="10"/>
 
-            <property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
+            <!-- Automatic schema export -->
+            <property name="javax.persistence.schema-generation.database.action"
+                      value="drop-and-create"/>
 
-            <!--property name="hibernate.show_sql" value="true"/-->
+            <!-- SQL statement logging -->
             <property name="hibernate.format_sql" value="true"/>
+            <!--property name="hibernate.show_sql" value="true"/-->
+
         </properties>
 
     </persistence-unit>

hibernate-reactive-core/src/main/java/org/hibernate/reactive/boot/impl/ReactiveTypeContributor.java

@@ -1,3 +1,8 @@
+/* Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright: Red Hat Inc. and Hibernate Authors
+ */
 package org.hibernate.reactive.boot.impl;
 
 import org.hibernate.boot.model.TypeContributions;