Portal property module.framework.web.generator.excluded.paths lists JARs that portal already includes (or imports packages from) that are stripped from WABs.
For example, portal imports the Spring version 4.1.9 packages (see https://github.com/liferay/liferay-portal/blob/7.0.x/modules/core/portal-bootstrap/system.packages.extra.bnd) and therefore excludes their JARs from WABs. It uses a globing pattern to strip them out of WABs. Naming a JAR different from its glob pattern prevents it from being stripped from the WAB. You could for example rename your spring-aop.jar to include its version--spring-aop-3.0.7.RELEASE.jar.