[Java] Apply empty line checkstyle rule.

Author: mjpt777

config/checkstyle/checkstyle.xml

@@ -137,6 +137,11 @@
 
  <module name="MutableException"/>
 
+ <module name="EmptyLineSeparator">
+ <property name="allowNoEmptyLineBetweenFields" value="true"/>
+ <property name="tokens" value="IMPORT, CLASS_DEF, INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF"/>
+ </module>
+
  <module name="TodoComment">
  <property name="severity" value="info"/>
  <property name="format" value="TODO"/>