Drop JDO support

Issue: SPR-14130

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/ConnectionHandle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,14 +20,12 @@ import java.sql.Connection;
 
 /**
  * Simple interface to be implemented by handles for a JDBC Connection.
- * Used by JpaDialect and JdoDialect, for example.
+ * Used by JpaDialect, for example.
  *
  * @author Juergen Hoeller
  * @since 1.1
  * @see SimpleConnectionHandle
  * @see ConnectionHolder
- * @see org.springframework.orm.jdo.JpaDialect#getJdbcConnection
- * @see org.springframework.orm.jdo.JdoDialect#getJdbcConnection
  */
 public interface ConnectionHandle {
 

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/ConnectionHolder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -182,9 +182,7 @@ public class ConnectionHolder extends ResourceHolderSupport {
 	 * <p>This is necessary for ConnectionHandles that expect "Connection borrowing",
 	 * where each returned Connection is only temporarily leased and needs to be
 	 * returned once the data operation is done, to make the Connection available
-	 * for other operations within the same transaction. This is the case with
-	 * JDO 2.0 DataStoreConnections, for example.
-	 * @see org.springframework.orm.jdo.DefaultJdoDialect#getJdbcConnection
+	 * for other operations within the same transaction.
 	 */
 	@Override
 	public void released() {