SONAR suggestion - generic exceptions

Replace uses of generic RuntimeException
with more appropriate unchecked exceptions

Change-Id: If283743c2cf7252b8d280bdb788708ebbe57da9d
diff --git a/core/net/src/main/java/org/onosproject/net/pi/impl/PiFlowRuleTranslatorImpl.java b/core/net/src/main/java/org/onosproject/net/pi/impl/PiFlowRuleTranslatorImpl.java
index 430e5e1..3230f41 100644
--- a/core/net/src/main/java/org/onosproject/net/pi/impl/PiFlowRuleTranslatorImpl.java
+++ b/core/net/src/main/java/org/onosproject/net/pi/impl/PiFlowRuleTranslatorImpl.java
@@ -428,7 +428,7 @@
                     return fieldMatch;
                 default:
                     // Should never be here.
-                    throw new RuntimeException(
+                    throw new IllegalArgumentException(
                             "Unrecognized match type " + fieldModel.matchType().name());
             }
         } catch (ByteSequenceTrimException e) {