Restrict visibility of only locally used function

Change-Id: Ife648c8ddbdfbf4858c4139744c43de6c4598934
diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/bz/BugzillaClient.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/bz/BugzillaClient.java
index 5abbf42..c05cad1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/bz/BugzillaClient.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/bz/BugzillaClient.java
@@ -115,7 +115,7 @@
     return fields;
   }
 
-  public Set<String> getLegalValues(Fields field) throws BugzillaException {
+  private Set<String> getLegalValues(Fields field) throws BugzillaException {
     if (legalFieldValues.get(field) == null) {
       GetLegalValues getValues = new GetLegalValues(field);
       connector.executeMethod(getValues);