Revert "Update checkstyle.xml"

This reverts commit 4192898.

Author: SirCotare

src/main/resources/checkstyle.xml

@@ -117,7 +117,7 @@
         <module name="LocalFinalVariableName"/>
         <module name="LocalVariableName"/>
         <module name="MemberName">
-            <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
+            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
             <message key="name.invalidPattern"
                      value="Member name ''{0}'' must match pattern ''{1}''."/>
         </module>