parquet-column/src/main/java/org/apache/parquet/filter2/predicate/ValidTypeMap.java
private static void add(Class<?> c, PrimitiveTypeName p) {
    Set<PrimitiveTypeName> descriptors = classToParquetType.get(c);
    if (descriptors == null) {
      descriptors = new HashSet<PrimitiveTypeName>();
      classToParquetType.put(c, descriptors);
    }
    descriptors.add(p);

    Set<Class<?>> classes = parquetTypeToClass.get(p);
    if (classes == null) {
      classes = new HashSet<Class<?>>();
      parquetTypeToClass.put(p, classes);
    }
    classes.add(c);
  }
private static void add(Class<?> c, PrimitiveTypeName p) {
    Set<PrimitiveTypeName> descriptors = classToParquetType.get(c);
    if (descriptors == null) {
      descriptors = new HashSet<PrimitiveTypeName>();
      classToParquetType.put(c, descriptors);
    }
    descriptors.add(p);

    Set<Class<?>> classes = parquetTypeToClass.get(p);
    if (classes == null) {
      classes = new HashSet<Class<?>>();
      parquetTypeToClass.put(p, classes);
    }
    classes.add(c);
  }
set up the mapping in both directions