Several Android apps (especially the ones by Google) feature a section with a list of open source libraries used in the app and for each of them, a full text of its licence. This usually involves the Apache License, which is used in most of the common Android libraries, such as ActionBarSherlock, ViewPagerIndicator, Guava etc.
Is it mandatory to include such attribution in order to comply with the terms of the (Apache) license?
How should this section look? If multiple libraries use the same license, is it necessary to duplicate the text of the license for each of them?
Is it even necessary to include the whole text of the license, or is the sole copyright notice enough (see the appendix here: http://www.apache.org/licenses/LICENSE-2.0)?
Do the official Android developer guidelines feature some information on this topic (I failed to find any)?
The Apache 2 license does not require attribution in their derived products advertising materials but I in my opinion it is often considered as “a nice thing to do” to support the developers of those libraries.
The attribution requirement “‘advertising clause'” was removed in the Apache 1.1 license:
The 1.1 version of the Apache License was approved by the ASF in 2000. The primary change from the 1.0 license is in the ‘advertising clause’ (section 3 of the 1.0 license); derived products are no longer required to include attribution in their advertising materials, only in their documentation.
Other open source software licenses have different requirements.