Merge pull request #3973 from LinuxForHealth/issue-3957-narrow-conv

issue #3957 avoid narrowing conversion flagged by CodeQL

Author: lmsurpre

fhir-persistence/src/main/java/org/linuxforhealth/fhir/persistence/util/InputOutputByteStream.java

@@ -129,17 +129,18 @@ public int read(byte b[], int off, int len) throws IOException {
 
         @Override
         public long skip(long n) {
-            if (n < 0) {
+            if (n <= 0) {
                 return 0;
             }
 
             // don't try to skip more than we have left
-            long remaining = offset - posn;
+            final int remaining = offset - posn;
             if (n > remaining) {
                 n = remaining;
             }
 
-            posn += n;
+            // it is safe to convert to int here because we have already checked the bound above
+            posn += (int)n;
             return n;
         }