Add missing license headers

(cherry picked from commit 9abe775708)

hibernate-testing/src/main/java/org/hibernate/testing/jdbc/leak/ConnectionLeakUtil.java

@@ -16,6 +16,9 @@ import org.hibernate.dialect.Dialect;
 
 import org.hibernate.testing.jdbc.JdbcProperties;
 
+/**
+ * @author Vlad Mihalcea
+ */
 public class ConnectionLeakUtil {
 
 	private JdbcProperties jdbcProperties = JdbcProperties.INSTANCE;

hibernate-testing/src/main/java/org/hibernate/testing/jdbc/leak/H2IdleConnectionCounter.java

@@ -1,3 +1,9 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
 package org.hibernate.testing.jdbc.leak;
 
 import java.sql.Connection;

hibernate-testing/src/main/java/org/hibernate/testing/jdbc/leak/MySQLIdleConnectionCounter.java

@@ -1,3 +1,9 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
 package org.hibernate.testing.jdbc.leak;
 
 import java.sql.Connection;

hibernate-testing/src/main/java/org/hibernate/testing/jdbc/leak/OracleIdleConnectionCounter.java

@@ -1,3 +1,9 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
 package org.hibernate.testing.jdbc.leak;
 
 import java.sql.Connection;

hibernate-testing/src/main/java/org/hibernate/testing/jdbc/leak/PostgreSQLIdleConnectionCounter.java

@@ -1,3 +1,9 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
 package org.hibernate.testing.jdbc.leak;
 
 import java.sql.Connection;