Avoid use of Objects.hash when there's only 1 params

- directly call #hashCode() when hashed Object seems non-null
- replace with Objects.hashCode(Object) when Nullable
- replace with Long.hashCode(long), etc. when primitive

Change-Id: I08c24ebbe94cf4162d1491209a14baf953163e41
diff --git a/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/tableservice/AbstractOvsdbTableService.java b/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/tableservice/AbstractOvsdbTableService.java
index 6b7c797..af1a01d 100644
--- a/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/tableservice/AbstractOvsdbTableService.java
+++ b/ovsdb/rfc/src/main/java/org/onosproject/ovsdb/rfc/tableservice/AbstractOvsdbTableService.java
@@ -210,7 +210,7 @@
             return null;
         }
         ColumnDescription columnDesc = new ColumnDescription("_uuid", "getTableUuidColumn");
-        return (Column) getColumnHandler(columnDesc);
+        return getColumnHandler(columnDesc);
     }
 
     @Override
@@ -228,7 +228,7 @@
             return null;
         }
         ColumnDescription columnDesc = new ColumnDescription("_version", "getTableVersionColumn");
-        return (Column) getColumnHandler(columnDesc);
+        return getColumnHandler(columnDesc);
     }
 
     /**
@@ -260,7 +260,7 @@
 
     @Override
     public int hashCode() {
-        return Objects.hash(row);
+        return row.hashCode();
     }
 
     @Override
@@ -277,7 +277,7 @@
 
     @Override
     public String toString() {
-        TableSchema schema = (TableSchema) getTableSchema();
+        TableSchema schema = getTableSchema();
         String tableName = schema.name();
         return toStringHelper(this).add("tableName", tableName).add("row", row).toString();
     }