General upgrade from core lib 0.6.1 to 0.6.10, minor build updates

While the current build pattern is out of date, it is closer to being what is currently being implemented in our projects. This is the first set of changes for this project to at least modernize the code and stabalize the build. Future changes will be made to further upgrade this application to use a more secure build pattern.

src/main/java/org/eclipsefoundation/downloads/dto/DownloadFileIndex.java

@@ -40,8 +40,6 @@ public class DownloadFileIndex extends BareNode {
     @NotNull
     private int downloadCount;
     @NotNull
-    private int sizeDiskBytes;
-    @NotNull
     private long timestampDisk;
     private String md5sum;
     private String sha1sum;
@@ -93,20 +91,6 @@ public class DownloadFileIndex extends BareNode {
         this.downloadCount = downloadCount;
     }
 
-    /**
-     * @return the sizeDiskBytes
-     */
-    public int getSizeDiskBytes() {
-        return sizeDiskBytes;
-    }
-
-    /**
-     * @param sizeDiskBytes the sizeDiskBytes to set
-     */
-    public void setSizeDiskBytes(int sizeDiskBytes) {
-        this.sizeDiskBytes = sizeDiskBytes;
-    }
-
     /**
      * @return the timestampDisk
      */