I want to upgrade from Hadoop 1.2 to 2.2. I am using Maven and I want to upgrade without any problems due to upgrade. How can I do this?
This is what I have now: 
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-core</artifactId>
    <version>1.2.1</version>
</dependency>