Step 1: Download latest RestEasy distribution from here
Step 2: Unzip and store it in some suitable location. For example
Step 3: Go to JBoss Application Server location in your local drive for example “D:\jboss-as-7.1.1.Final”
Step 4: Open “modules” folder from above location. Delete the old version and copy new version into respective packages
Step 5: For example, this package “org.jboss.resteasy“ in local drive “D:\jboss-as-7.1.1.Final\modules” contains all resteasy related jars
Step 6: Delete all folders at this location and jars inside them (older version)
Step 7: Copy latest RestEasy distribution from downloaded source
Step 8: Paste the respective jars into this location from downloaded latest resteasy distribution (Browse this folder resteasy-jboss-modules-3.0.7.Final from downloaded distribution for latest RestEasy version)