pom.xml diagnostics don't recognize unsupported tags

[tolusha]

jdt.ls doesn't report any issues if unsupported tag is used;

        <dependency>
            <groupId>com.google.inject</groupId>
            <artifactId>guice</artifactId>
            <unsupported-tag>value</unsupported-tag>
        </dependency>

[fbricon]

I'm going to close it as out-of-scope. SInce this is purely an XML validation issue, already covered by lsp4xml.