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/PiUtils.java b/core/net/src/main/java/org/onosproject/net/pi/impl/PiUtils.java
index 78bca5f..6f8d33a 100644
--- a/core/net/src/main/java/org/onosproject/net/pi/impl/PiUtils.java
+++ b/core/net/src/main/java/org/onosproject/net/pi/impl/PiUtils.java
@@ -54,7 +54,8 @@
                         .orElse(null)
                         .newInstance();
             } catch (InstantiationException | IllegalAccessException e) {
-                throw new RuntimeException(format("Unable to instantiate interpreter of pipeconf %s", pipeconf.id()));
+                throw new IllegalArgumentException(format("Unable to instantiate interpreter of pipeconf %s",
+                                                          pipeconf.id()));
             }
         }
     }