docs: void addColumn(String family, String qualifier, Class<?> clazz) {
  		Preconditions.checkNotNull(family, "family name");
  		Preconditions.checkNotNull(qualifier, "qualifier name");
  		Preconditions.checkNotNull(clazz, "class type");
  		Map<String, TypeInformation<?>> qualifierMap = this.familyMap.get(family);
  
  		if (!HBaseRowInputFormat.isSupportedType(clazz)) {
  			// throw exception
  			throw new IllegalArgumentException("Unsupported class type found " + clazz + ". " +
  				"Better to use byte[].class and deserialize using user defined scalar functions");
  		}
  
  		if (qualifierMap == null) {
  			qualifierMap = new LinkedHashMap<>();
  		}
  		qualifierMap.put(qualifier, TypeExtractor.getForClass(clazz));
  		familyMap.put(family, qualifierMap);
  	}