找不到元素doctrine-mongo-mapping的声明

I'm trying to debug a website written with Symfony 2 using Eclipse Mars. After solving the Composer dependencies (the ones from composer.json), and setting up the database, I cannot get past this error, and I could not find any clue on the web. Any suggestion?

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UPDATE: I ran another Composer update, cleaned and built and now I have four instances of the same error:

White spaces are required between publicId and systemId.

Each instance of the error matches a doctrine xml: Group.mongodb.xml, User.mongodb.xml, Group.orm.xml, User.orm.xml.

In the xsi:schemaLocation attribute, switching the two URLs solved it (the one ending in .xsd goes first)