Added some additional checkstyle/pmd checks (#406)

Checkstyle:
- Change NewlineAtEndOfFile (error): Changed no new line at end of file
to error (we always keep commenting on it. So if it's an error people
have to fix it right away).
- EqualsAvoidNull (warning): Give warning when constant not at the left
side of equals.

PMD:
- Added CompareObjectsWithEquals (error): Use equals to compare objects.
- UseCollectionIsEmpty (warning): Use isEmpty() to check if collection
is empty.
- SimplifyBooleanReturns (info)
- UnusedLocalVariable (info)
- UnusedPrivateField (info)
- UnusedPrivateMethod (info)

Signed-off-by: Hilbrand Bouwkamp <hilbrand@h72.nl>

Author: Hilbrand

sat-plugin/src/main/resources/rulesets/checkstyle/rules.xml

@@ -43,7 +43,7 @@
 	</module>
 
 	<module name="NewlineAtEndOfFile">
-		<property name="severity" value="info"/>
+		<property name="severity" value="error"/>
 	</module>
 
 	<module name="org.openhab.tools.analysis.checkstyle.ExportInternalPackageCheck">
@@ -288,5 +288,8 @@
 		<module name="MemberName">
 			<property name="severity" value="info"/>
 		</module>
+		<module name="EqualsAvoidNull">
+			<property name="severity" value="warning"/>
+		</module>
 	</module>
 </module>

sat-plugin/src/main/resources/rulesets/pmd/rules.xml

@@ -55,6 +55,9 @@
 	<rule ref="category/java/errorprone.xml/DoNotThrowExceptionInFinally">
 		<priority>2</priority>
 	</rule>
+	<rule ref="category/java/errorprone.xml/CompareObjectsWithEquals">
+		<priority>1</priority>
+	</rule>
 	<rule ref="category/java/errorprone.xml/EqualsNull">
 		<priority>1</priority>
 	</rule>
@@ -67,6 +70,9 @@
 	<rule ref="category/java/errorprone.xml/CompareObjectsWithEquals">
 		<priority>3</priority>
 	</rule>
+	<rule ref="category/java/bestpractices.xml/UseCollectionIsEmpty">
+		<priority>2</priority>
+	</rule>
 
 	<!-- See https://pmd.github.io/pmd-6.7.0/pmd_rules_java_multithreading.html -->
 	<rule ref="category/java/multithreading.xml/DontCallThreadRun">
@@ -78,6 +84,16 @@
 	<rule ref="category/java/multithreading.xml/UnsynchronizedStaticFormatter">
 		<priority>3</priority>
 	</rule>
+	<rule ref="category/java/bestpractices.xml/UnusedLocalVariable">
+		<priority>3</priority>
+	</rule>
+	<rule ref="category/java/bestpractices.xml/UnusedPrivateField">
+		<priority>3</priority>
+	</rule>
+	<rule ref="category/java/bestpractices.xml/UnusedPrivateMethod">
+		<priority>3</priority>
+	</rule>
+
 
 	<!-- See https://pmd.github.io/pmd-6.7.0/pmd_rules_java_bestpractices.html -->
 	<rule ref="category/java/bestpractices.xml/AvoidPrintStackTrace">
@@ -100,6 +116,9 @@
 	<rule ref="category/java/design.xml/SimplifyBooleanExpressions">
 		<priority>3</priority>
 	</rule>
+	<rule ref="category/java/design.xml/SimplifyBooleanReturns">
+		<priority>3</priority>
+	</rule>
 
 	<!-- See https://pmd.github.io/pmd-6.7.0/pmd_rules_java_performance.html -->
 	<rule ref="category/java/performance.xml/AvoidArrayLoops">