Clarify and clean up some PiPipelineInterpreter usages
Change-Id: I3f48141e72d552259109aba20a6b34a93d94735a
diff --git a/core/api/src/main/java/org/onosproject/net/pi/model/PiPipelineInterpreter.java b/core/api/src/main/java/org/onosproject/net/pi/model/PiPipelineInterpreter.java
index 1068026..ccf2733 100644
--- a/core/api/src/main/java/org/onosproject/net/pi/model/PiPipelineInterpreter.java
+++ b/core/api/src/main/java/org/onosproject/net/pi/model/PiPipelineInterpreter.java
@@ -64,7 +64,8 @@
/**
* Returns an integer table ID equivalent to the given PI table ID. If not present, it means that the given PI table
- * ID refers to a table that does not exist, or that cannot be used for flow rule operations.
+ * ID cannot be mapped to any integer table ID, because such mapping would be meaningless or because such PI table
+ * ID is not defined by the pipeline model.
*
* @param piTableId PI table ID
* @return numeric table ID
@@ -84,8 +85,10 @@
throws PiInterpreterException;
/**
- * Returns a PI direct counter ID for the given table, if present. If not present, it means that the given table
- * does not support direct counters.
+ * Returns a PI direct counter ID for the given table to be used to to compute flow entry statistics, if present. If
+ * not present, it means that the given table does not offer any counter suitable for the purpose of computing flow
+ * rule statistics. Other direct counters might be defined for the given table (check pipeline model), however none
+ * of them should be used for flow entry statistics except for this one.
*
* @param piTableId table ID
* @return optional direct counter ID