deactivated PMD's UR anomaly rule

conf/quality-config/pmd-ruleset.xml

@@ -65,6 +65,14 @@
 		<exclude name="AvoidUsingVolatile" />
 	</rule>
 
+	<!-- UR means "undefined reference" which is already detected by the compiler. 
+		so we deactivate it. -->
+	<rule ref="rulesets/java/controversial.xml/DataflowAnomalyAnalysis">
+		<properties>
+			<property name="violationSuppressRegex" value="^Found 'UR'-anomaly.*" />
+		</properties>
+	</rule>
+
 	<rule ref="rulesets/java/coupling.xml">
 		<exclude name="LawOfDemeter" />
 	</rule>

src/main/java/teetime/framework/ExecutionInstantiation.java

@@ -66,10 +66,7 @@ class ExecutionInstantiation {
 			final OutputPort outputPort, final InstantiationPipe pipe) {
 		Stage targetStage = pipe.getTargetPort().getOwningStage();
 
-		int targetColor = DEFAULT_COLOR;
-		if (colors.containsKey(targetStage)) {
-			targetColor = colors.get(targetStage);
-		}
+		int targetColor = colors.containsKey(targetStage) ? colors.get(targetStage) : DEFAULT_COLOR;
 
 		if (threadableStages.contains(targetStage) && targetColor != color) {
 			if (pipe.capacity() != 0) {