Suppress XML DTD error in Eclipse

The XML DTD for a Joomla component is not correct, it does not contain the method="install/upgrade" attribute. In eclipse it is annoying me because there is a permanent error showing for my project.

Is there a way to suppress this particular XML DTD error, while allowing other xml error checking开发者_如何学JAVA to take place in the file?

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Preferences -> XML -> XML Files -> Validation -> "Indicate when no grammar is specified" = "Ignore"