Rename internal variable to provided_keys

More directly describes what the local holds — the keys the caller
actually provided — than the previous candidates/competitors names.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yahonda

lib/plsql/connection.rb

@@ -20,13 +20,13 @@ class Connection
     # branch on :database vs :sid. Raises ArgumentError on conflicts or
     # invalid values.
     def self.resolve_database_aliases!(params)
-      candidates = []
-      candidates << ":database"     if params[:database]
-      candidates << ":service_name" if params[:service_name]
-      candidates << ":sid"          if params[:sid]
-      if candidates.size > 1
+      provided_keys = []
+      provided_keys << ":database"     if params[:database]
+      provided_keys << ":service_name" if params[:service_name]
+      provided_keys << ":sid"          if params[:sid]
+      if provided_keys.size > 1
         raise ArgumentError,
-          "Cannot specify more than one of #{candidates.join(', ')}; they are mutually exclusive."
+          "Cannot specify more than one of #{provided_keys.join(', ')}; they are mutually exclusive."
       end
 
       if (svc = params[:service_name])