fix: if the max ordinal for a map value is zero then reserve 1 bit fo…

…r it instead of nothing

hollow/src/main/java/com/netflix/hollow/core/write/HollowMapTypeWriteState.java

@@ -134,7 +134,7 @@ private void gatherStatistics() {
         }
 
         bitsPerKeyElement = 64 - Long.numberOfLeadingZeros(maxKeyOrdinal + 1);
-        bitsPerValueElement = 64 - Long.numberOfLeadingZeros(maxValueOrdinal);
+        bitsPerValueElement = maxValueOrdinal == 0 ? 1 : 64 - Long.numberOfLeadingZeros(maxValueOrdinal);
 
         bitsPerMapSizeValue = 64 - Long.numberOfLeadingZeros(maxMapSize);