code: private static Map<String, Integer> monthsMapping() {
          final Map<String, Integer> stringMapping = new HashMap<>();
          stringMapping.put("JAN", 1);
          stringMapping.put("FEB", 2);
          stringMapping.put("MAR", 3);
          stringMapping.put("APR", 4);
          stringMapping.put("MAY", 5);
          stringMapping.put("JUN", 6);
          stringMapping.put("JUL", 7);
          stringMapping.put("AUG", 8);
          stringMapping.put("SEP", 9);
          stringMapping.put("OCT", 10);
          stringMapping.put("NOV", 11);
          stringMapping.put("DEC", 12);
          return stringMapping;
      }
docs: Creates months mapping.
  
  @return Map where strings month names in EEE format, and integers correspond to their 1-12 mappings