Allow if-nesting with depth of 4.

Yes, it brings a congnitive challenge right now,
but on the other hand the refactoring of the
`DefaultNeo4jEntityConverter#createInstanceOfRelationships`
is a challenge on its own.

Author: meistermeier

etc/checkstyle/config.xml

@@ -43,7 +43,7 @@
             <property name="max" value="3" />
         </module>
         <module name="com.puppycrawl.tools.checkstyle.checks.coding.NestedIfDepthCheck">
-            <property name="max" value="3" />
+            <property name="max" value="4" />
         </module>
         <module name="com.puppycrawl.tools.checkstyle.checks.coding.NestedTryDepthCheck">
             <property name="max" value="3" />