add a comment about autocommit in Hikari

Author: gavinking

hibernate-c3p0/src/main/java/org/hibernate/c3p0/internal/C3P0ConnectionProvider.java

@@ -144,6 +144,10 @@ public void configure(Map<String, Object> properties) {
 
 		loadDriverClass( jdbcDriverClass );
 
+		// c3p0 returns Connections with autocommit enabled, but for
+		// historical reasons we default to calling setAutocommit(false)
+		// as soon as we obtain a new connection. This maybe isn't ideal,
+		// and it's not what we do with Agroal or Hikari.
 		autocommit = getBoolean( JdbcSettings.AUTOCOMMIT, properties ); // defaults to false
 		isolation = ConnectionProviderInitiator.extractIsolation( properties );
 

hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/DriverManagerConnectionProviderImpl.java

@@ -86,7 +86,7 @@ public void configure(Map<String, Object> configurationValues) {
 	}
 
 	private PooledConnections buildPool(Map<String,Object> configurationValues, ServiceRegistryImplementor serviceRegistry) {
-		final boolean autoCommit = ConfigurationHelper.getBoolean( AvailableSettings.AUTOCOMMIT, configurationValues );
+		final boolean autoCommit = ConfigurationHelper.getBoolean( AvailableSettings.AUTOCOMMIT, configurationValues ); // default to false
 		final int minSize = ConfigurationHelper.getInt( MIN_SIZE, configurationValues, 1 );
 		final int maxSize = ConfigurationHelper.getInt( AvailableSettings.POOL_SIZE, configurationValues, 20 );
 		final int initialSize = ConfigurationHelper.getInt( INITIAL_SIZE, configurationValues, minSize );

hibernate-hikaricp/src/main/java/org/hibernate/hikaricp/internal/HikariCPConnectionProvider.java

@@ -97,8 +97,9 @@ public DatabaseConnectionInfo getDatabaseConnectionInfo(Dialect dialect) {
 		return new DatabaseConnectionInfoImpl(
 				HikariCPConnectionProvider.class,
 				hikariConfig.getJdbcUrl(),
-				// Attempt to resolve the driver name from the dialect, in case it wasn't explicitly set and access to
-				// the database metadata is allowed
+				// Attempt to resolve the driver name from the dialect,
+				// in case it wasn't explicitly set and access to the
+				// database metadata is allowed
 				isBlank( hikariConfig.getDriverClassName() )
 						? extractDriverNameFromMetadata()
 						: hikariConfig.getDriverClassName(),