[NO ISSUE][*DB] Refactor UDF auth header access

Change-Id: I41023663e1212c0c8789873e63c9bfbeae48cea8
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/17390
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Murtadha Hubail <mhubail@apache.org>
diff --git a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/NCUdfApiServlet.java b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/NCUdfApiServlet.java
index 3d0f7fc..47685d8 100644
--- a/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/NCUdfApiServlet.java
+++ b/asterixdb/asterix-app/src/main/java/org/apache/asterix/api/http/server/NCUdfApiServlet.java
@@ -81,7 +81,7 @@
     protected final IReceptionist receptionist;
 
     protected Path workingDir;
-    protected String sysAuthHeader;
+    private String sysAuthHeader;
     private ILibraryManager libraryManager;
     private int timeout;
 
@@ -250,7 +250,7 @@
                 }
                 URI downloadURI = createDownloadURI(libraryTempFile);
                 doCreate(dvAndName.getFirst(), dvAndName.getSecond(), language,
-                        ExternalLibraryUtils.digestToHexString(digest), downloadURI, true, sysAuthHeader,
+                        ExternalLibraryUtils.digestToHexString(digest), downloadURI, true, getSysAuthHeader(),
                         requestReference, request);
             } else if (op == LibraryOperation.DELETE) {
                 //DELETE semantics imply ifExists
@@ -281,6 +281,10 @@
         }
     }
 
+    protected String getSysAuthHeader() {
+        return sysAuthHeader;
+    }
+
     private void writeException(Exception e, IServletResponse response) {
         response.setStatus(toHttpErrorStatus(e));
         PrintWriter responseWriter = response.writer();