The latest version of m2e that works with Flash Builder 4.7 is 126.96.36.19940328-1905 available at this update site: http://download.eclipse.org/technology/m2e/releases-for-indigo/1.4/
Flash Builder 4.7 is based on Eclipse Indigo and, while m2e no longer officially supports Indigo, the m2e team has created an additional update site to resolve some install issues and make 1.4 work. (ref)
- Add the above update site in Install New Software.
- Select both m2e - Maven Integration for Eclipse AND m2e - slf4j over logback logging (Optional). Flash Builder 4.7 comes with an older version of the optional logging feature and the only way to upgrade m2e is to also upgrade that.
- Click Next and Finish