demo usage of `annotation_metadata' flag

annotations.json

{
  "name": "annotations",
  "namespaces": {
    "java": "org.apache.anno.test"
  },
  "includes": [
  ],
  "enums": [
  ],
  "typedefs": [
  ],
  "structs": [
    {
      "name": "Person",
      "isException": false,
      "isUnion": false,
      "fields": [
        {
          "key": 1,
          "name": "name",
          "typeId": "string",
          "annotations":           {
            "access_level": "public"
          },
          "required": "required"
        },
        {
          "key": 2,
          "name": "phone",
          "typeId": "string",
          "annotations":           {
            "max_length": "12",
            "min_length": "5"
          },
          "required": "optional"
        },
        {
          "key": 3,
          "name": "addresses",
          "typeId": "list",
          "type": {
            "typeId": "list",
            "elemTypeId": "string"
          },
          "annotations":           {
            "non_empty": "true"
          },
          "required": "optional"
        }
      ]
    }
  ],
  "constants": [
  ],
  "services": [
  ]
}

annotations.thrift

namespace java org.apache.anno.test

struct Person {
  1: required string name (access_level = "public")
  2: optional string phone (min_length = "5", max_length = "12")
  3: optional list<string> addresses (non_empty = "true")
}

Person.java

/**
 * Autogenerated by Thrift Compiler (0.17.0)
 *
 * DO NOT EDIT UNLESS YOU ARE SURE THAT YOU KNOW WHAT YOU ARE DOING
 *  @generated
 */
package org.apache.anno.test;

@SuppressWarnings({"cast", "rawtypes", "serial", "unchecked", "unused"})
@javax.annotation.Generated(value = "Autogenerated by Thrift Compiler (0.17.0)", date = "2022-04-19")
public class Person implements org.apache.thrift.TBase<Person, Person._Fields>, java.io.Serializable, Cloneable, Comparable<Person> {
  private static final org.apache.thrift.protocol.TStruct STRUCT_DESC = new org.apache.thrift.protocol.TStruct("Person");

  private static final org.apache.thrift.protocol.TField NAME_FIELD_DESC = new org.apache.thrift.protocol.TField("name", org.apache.thrift.protocol.TType.STRING, (short)1);
  private static final org.apache.thrift.protocol.TField PHONE_FIELD_DESC = new org.apache.thrift.protocol.TField("phone", org.apache.thrift.protocol.TType.STRING, (short)2);
  private static final org.apache.thrift.protocol.TField ADDRESSES_FIELD_DESC = new org.apache.thrift.protocol.TField("addresses", org.apache.thrift.protocol.TType.LIST, (short)3);

  private static final org.apache.thrift.scheme.SchemeFactory STANDARD_SCHEME_FACTORY = new PersonStandardSchemeFactory();
  private static final org.apache.thrift.scheme.SchemeFactory TUPLE_SCHEME_FACTORY = new PersonTupleSchemeFactory();

  public @org.apache.thrift.annotation.Nullable java.lang.String name; // required
  public @org.apache.thrift.annotation.Nullable java.lang.String phone; // optional
  public @org.apache.thrift.annotation.Nullable java.util.List<java.lang.String> addresses; // optional

  /** The set of fields this struct contains, along with convenience methods for finding and manipulating them. */
  public enum _Fields implements org.apache.thrift.TFieldIdEnum {
    NAME((short)1, "name"),
    PHONE((short)2, "phone"),
    ADDRESSES((short)3, "addresses");

    private static final java.util.Map<java.lang.String, _Fields> byName = new java.util.HashMap<java.lang.String, _Fields>();

    static {
      for (_Fields field : java.util.EnumSet.allOf(_Fields.class)) {
        byName.put(field.getFieldName(), field);
      }
    }

    /**
     * Find the _Fields constant that matches fieldId, or null if its not found.
     */
    @org.apache.thrift.annotation.Nullable
    public static _Fields findByThriftId(int fieldId) {
      switch(fieldId) {
        case 1: // NAME
          return NAME;
        case 2: // PHONE
          return PHONE;
        case 3: // ADDRESSES
          return ADDRESSES;
        default:
          return null;
      }
    }

    /**
     * Find the _Fields constant that matches fieldId, throwing an exception
     * if it is not found.
     */
    public static _Fields findByThriftIdOrThrow(int fieldId) {
      _Fields fields = findByThriftId(fieldId);
      if (fields == null) throw new java.lang.IllegalArgumentException("Field " + fieldId + " doesn't exist!");
      return fields;
    }

    /**
     * Find the _Fields constant that matches name, or null if its not found.
     */
    @org.apache.thrift.annotation.Nullable
    public static _Fields findByName(java.lang.String name) {
      return byName.get(name);
    }

    private final short _thriftId;
    private final java.lang.String _fieldName;

    _Fields(short thriftId, java.lang.String fieldName) {
      _thriftId = thriftId;
      _fieldName = fieldName;
    }

    @Override
    public short getThriftFieldId() {
      return _thriftId;
    }

    @Override
    public java.lang.String getFieldName() {
      return _fieldName;
    }
  }

  // isset id assignments
  private static final _Fields optionals[] = {_Fields.PHONE,_Fields.ADDRESSES};
  public static final java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> metaDataMap;
  static {
    java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> tmpMap = new java.util.EnumMap<_Fields, org.apache.thrift.meta_data.FieldMetaData>(_Fields.class);
    tmpMap.put(_Fields.NAME, new org.apache.thrift.meta_data.FieldMetaData("name", org.apache.thrift.TFieldRequirementType.REQUIRED, 
        new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING), 
        java.util.stream.Stream.<java.util.Map.Entry<java.lang.String, java.lang.String>>builder()
            .add(new java.util.AbstractMap.SimpleImmutableEntry<>("access_level", "public"))
            .build().collect(java.util.stream.Collectors.toMap(java.util.Map.Entry::getKey, java.util.Map.Entry::getValue))));
    tmpMap.put(_Fields.PHONE, new org.apache.thrift.meta_data.FieldMetaData("phone", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
        new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING), 
        java.util.stream.Stream.<java.util.Map.Entry<java.lang.String, java.lang.String>>builder()
            .add(new java.util.AbstractMap.SimpleImmutableEntry<>("max_length", "12"))
            .add(new java.util.AbstractMap.SimpleImmutableEntry<>("min_length", "5"))
            .build().collect(java.util.stream.Collectors.toMap(java.util.Map.Entry::getKey, java.util.Map.Entry::getValue))));
    tmpMap.put(_Fields.ADDRESSES, new org.apache.thrift.meta_data.FieldMetaData("addresses", org.apache.thrift.TFieldRequirementType.OPTIONAL, 
        new org.apache.thrift.meta_data.ListMetaData(org.apache.thrift.protocol.TType.LIST, 
            new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)), 
        java.util.stream.Stream.<java.util.Map.Entry<java.lang.String, java.lang.String>>builder()
            .add(new java.util.AbstractMap.SimpleImmutableEntry<>("non_empty", "true"))
            .build().collect(java.util.stream.Collectors.toMap(java.util.Map.Entry::getKey, java.util.Map.Entry::getValue))));
    metaDataMap = java.util.Collections.unmodifiableMap(tmpMap);
    org.apache.thrift.meta_data.FieldMetaData.addStructMetaDataMap(Person.class, metaDataMap);
  }

  public Person() {
  }

  public Person(
    java.lang.String name)
  {
    this();
    this.name = name;
  }

  /**
   * Performs a deep copy on <i>other</i>.
   */
  public Person(Person other) {
    if (other.isSetName()) {
      this.name = other.name;
    }
    if (other.isSetPhone()) {
      this.phone = other.phone;
    }
    if (other.isSetAddresses()) {
      java.util.List<java.lang.String> __this__addresses = new java.util.ArrayList<java.lang.String>(other.addresses);
      this.addresses = __this__addresses;
    }
  }

  @Override
  public Person deepCopy() {
    return new Person(this);
  }

  @Override
  public void clear() {
    this.name = null;
    this.phone = null;
    this.addresses = null;
  }

  @org.apache.thrift.annotation.Nullable
  public java.lang.String getName() {
    return this.name;
  }

  public Person setName(@org.apache.thrift.annotation.Nullable java.lang.String name) {
    this.name = name;
    return this;
  }

  public void unsetName() {
    this.name = null;
  }

  /** Returns true if field name is set (has been assigned a value) and false otherwise */
  public boolean isSetName() {
    return this.name != null;
  }

  public void setNameIsSet(boolean value) {
    if (!value) {
      this.name = null;
    }
  }

  @org.apache.thrift.annotation.Nullable
  public java.lang.String getPhone() {
    return this.phone;
  }

  public Person setPhone(@org.apache.thrift.annotation.Nullable java.lang.String phone) {
    this.phone = phone;
    return this;
  }

  public void unsetPhone() {
    this.phone = null;
  }

  /** Returns true if field phone is set (has been assigned a value) and false otherwise */
  public boolean isSetPhone() {
    return this.phone != null;
  }

  public void setPhoneIsSet(boolean value) {
    if (!value) {
      this.phone = null;
    }
  }

  public int getAddressesSize() {
    return (this.addresses == null) ? 0 : this.addresses.size();
  }

  @org.apache.thrift.annotation.Nullable
  public java.util.Iterator<java.lang.String> getAddressesIterator() {
    return (this.addresses == null) ? null : this.addresses.iterator();
  }

  public void addToAddresses(java.lang.String elem) {
    if (this.addresses == null) {
      this.addresses = new java.util.ArrayList<java.lang.String>();
    }
    this.addresses.add(elem);
  }

  @org.apache.thrift.annotation.Nullable
  public java.util.List<java.lang.String> getAddresses() {
    return this.addresses;
  }

  public Person setAddresses(@org.apache.thrift.annotation.Nullable java.util.List<java.lang.String> addresses) {
    this.addresses = addresses;
    return this;
  }

  public void unsetAddresses() {
    this.addresses = null;
  }

  /** Returns true if field addresses is set (has been assigned a value) and false otherwise */
  public boolean isSetAddresses() {
    return this.addresses != null;
  }

  public void setAddressesIsSet(boolean value) {
    if (!value) {
      this.addresses = null;
    }
  }

  @Override
  public void setFieldValue(_Fields field, @org.apache.thrift.annotation.Nullable java.lang.Object value) {
    switch (field) {
    case NAME:
      if (value == null) {
        unsetName();
      } else {
        setName((java.lang.String)value);
      }
      break;

    case PHONE:
      if (value == null) {
        unsetPhone();
      } else {
        setPhone((java.lang.String)value);
      }
      break;

    case ADDRESSES:
      if (value == null) {
        unsetAddresses();
      } else {
        setAddresses((java.util.List<java.lang.String>)value);
      }
      break;

    }
  }

  @org.apache.thrift.annotation.Nullable
  @Override
  public java.lang.Object getFieldValue(_Fields field) {
    switch (field) {
    case NAME:
      return getName();

    case PHONE:
      return getPhone();

    case ADDRESSES:
      return getAddresses();

    }
    throw new java.lang.IllegalStateException();
  }

  /** Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise */
  @Override
  public boolean isSet(_Fields field) {
    if (field == null) {
      throw new java.lang.IllegalArgumentException();
    }

    switch (field) {
    case NAME:
      return isSetName();
    case PHONE:
      return isSetPhone();
    case ADDRESSES:
      return isSetAddresses();
    }
    throw new java.lang.IllegalStateException();
  }

  @Override
  public boolean equals(java.lang.Object that) {
    if (that instanceof Person)
      return this.equals((Person)that);
    return false;
  }

  public boolean equals(Person that) {
    if (that == null)
      return false;
    if (this == that)
      return true;

    boolean this_present_name = true && this.isSetName();
    boolean that_present_name = true && that.isSetName();
    if (this_present_name || that_present_name) {
      if (!(this_present_name && that_present_name))
        return false;
      if (!this.name.equals(that.name))
        return false;
    }

    boolean this_present_phone = true && this.isSetPhone();
    boolean that_present_phone = true && that.isSetPhone();
    if (this_present_phone || that_present_phone) {
      if (!(this_present_phone && that_present_phone))
        return false;
      if (!this.phone.equals(that.phone))
        return false;
    }

    boolean this_present_addresses = true && this.isSetAddresses();
    boolean that_present_addresses = true && that.isSetAddresses();
    if (this_present_addresses || that_present_addresses) {
      if (!(this_present_addresses && that_present_addresses))
        return false;
      if (!this.addresses.equals(that.addresses))
        return false;
    }

    return true;
  }

  @Override
  public int hashCode() {
    int hashCode = 1;

    hashCode = hashCode * 8191 + ((isSetName()) ? 131071 : 524287);
    if (isSetName())
      hashCode = hashCode * 8191 + name.hashCode();

    hashCode = hashCode * 8191 + ((isSetPhone()) ? 131071 : 524287);
    if (isSetPhone())
      hashCode = hashCode * 8191 + phone.hashCode();

    hashCode = hashCode * 8191 + ((isSetAddresses()) ? 131071 : 524287);
    if (isSetAddresses())
      hashCode = hashCode * 8191 + addresses.hashCode();

    return hashCode;
  }

  @Override
  public int compareTo(Person other) {
    if (!getClass().equals(other.getClass())) {
      return getClass().getName().compareTo(other.getClass().getName());
    }

    int lastComparison = 0;

    lastComparison = java.lang.Boolean.compare(isSetName(), other.isSetName());
    if (lastComparison != 0) {
      return lastComparison;
    }
    if (isSetName()) {
      lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.name, other.name);
      if (lastComparison != 0) {
        return lastComparison;
      }
    }
    lastComparison = java.lang.Boolean.compare(isSetPhone(), other.isSetPhone());
    if (lastComparison != 0) {
      return lastComparison;
    }
    if (isSetPhone()) {
      lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.phone, other.phone);
      if (lastComparison != 0) {
        return lastComparison;
      }
    }
    lastComparison = java.lang.Boolean.compare(isSetAddresses(), other.isSetAddresses());
    if (lastComparison != 0) {
      return lastComparison;
    }
    if (isSetAddresses()) {
      lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.addresses, other.addresses);
      if (lastComparison != 0) {
        return lastComparison;
      }
    }
    return 0;
  }

  @org.apache.thrift.annotation.Nullable
  @Override
  public _Fields fieldForId(int fieldId) {
    return _Fields.findByThriftId(fieldId);
  }

  @Override
  public void read(org.apache.thrift.protocol.TProtocol iprot) throws org.apache.thrift.TException {
    scheme(iprot).read(iprot, this);
  }

  @Override
  public void write(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {
    scheme(oprot).write(oprot, this);
  }

  @Override
  public java.lang.String toString() {
    java.lang.StringBuilder sb = new java.lang.StringBuilder("Person(");
    boolean first = true;

    sb.append("name:");
    if (this.name == null) {
      sb.append("null");
    } else {
      sb.append(this.name);
    }
    first = false;
    if (isSetPhone()) {
      if (!first) sb.append(", ");
      sb.append("phone:");
      if (this.phone == null) {
        sb.append("null");
      } else {
        sb.append(this.phone);
      }
      first = false;
    }
    if (isSetAddresses()) {
      if (!first) sb.append(", ");
      sb.append("addresses:");
      if (this.addresses == null) {
        sb.append("null");
      } else {
        sb.append(this.addresses);
      }
      first = false;
    }
    sb.append(")");
    return sb.toString();
  }

  public void validate() throws org.apache.thrift.TException {
    // check for required fields
    if (name == null) {
      throw new org.apache.thrift.protocol.TProtocolException("Required field 'name' was not present! Struct: " + toString());
    }
    // check for sub-struct validity
  }

  private void writeObject(java.io.ObjectOutputStream out) throws java.io.IOException {
    try {
      write(new org.apache.thrift.protocol.TCompactProtocol(new org.apache.thrift.transport.TIOStreamTransport(out)));
    } catch (org.apache.thrift.TException te) {
      throw new java.io.IOException(te);
    }
  }

  private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, java.lang.ClassNotFoundException {
    try {
      read(new org.apache.thrift.protocol.TCompactProtocol(new org.apache.thrift.transport.TIOStreamTransport(in)));
    } catch (org.apache.thrift.TException te) {
      throw new java.io.IOException(te);
    }
  }

  private static class PersonStandardSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
    @Override
    public PersonStandardScheme getScheme() {
      return new PersonStandardScheme();
    }
  }

  private static class PersonStandardScheme extends org.apache.thrift.scheme.StandardScheme<Person> {

    @Override
    public void read(org.apache.thrift.protocol.TProtocol iprot, Person struct) throws org.apache.thrift.TException {
      org.apache.thrift.protocol.TField schemeField;
      iprot.readStructBegin();
      while (true)
      {
        schemeField = iprot.readFieldBegin();
        if (schemeField.type == org.apache.thrift.protocol.TType.STOP) { 
          break;
        }
        switch (schemeField.id) {
          case 1: // NAME
            if (schemeField.type == org.apache.thrift.protocol.TType.STRING) {
              struct.name = iprot.readString();
              struct.setNameIsSet(true);
            } else { 
              org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
            }
            break;
          case 2: // PHONE
            if (schemeField.type == org.apache.thrift.protocol.TType.STRING) {
              struct.phone = iprot.readString();
              struct.setPhoneIsSet(true);
            } else { 
              org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
            }
            break;
          case 3: // ADDRESSES
            if (schemeField.type == org.apache.thrift.protocol.TType.LIST) {
              {
                org.apache.thrift.protocol.TList _list0 = iprot.readListBegin();
                struct.addresses = new java.util.ArrayList<java.lang.String>(_list0.size);
                @org.apache.thrift.annotation.Nullable java.lang.String _elem1;
                for (int _i2 = 0; _i2 < _list0.size; ++_i2)
                {
                  _elem1 = iprot.readString();
                  struct.addresses.add(_elem1);
                }
                iprot.readListEnd();
              }
              struct.setAddressesIsSet(true);
            } else { 
              org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
            }
            break;
          default:
            org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
        }
        iprot.readFieldEnd();
      }
      iprot.readStructEnd();

      // check for required fields of primitive type, which can't be checked in the validate method
      struct.validate();
    }

    @Override
    public void write(org.apache.thrift.protocol.TProtocol oprot, Person struct) throws org.apache.thrift.TException {
      struct.validate();

      oprot.writeStructBegin(STRUCT_DESC);
      if (struct.name != null) {
        oprot.writeFieldBegin(NAME_FIELD_DESC);
        oprot.writeString(struct.name);
        oprot.writeFieldEnd();
      }
      if (struct.phone != null) {
        if (struct.isSetPhone()) {
          oprot.writeFieldBegin(PHONE_FIELD_DESC);
          oprot.writeString(struct.phone);
          oprot.writeFieldEnd();
        }
      }
      if (struct.addresses != null) {
        if (struct.isSetAddresses()) {
          oprot.writeFieldBegin(ADDRESSES_FIELD_DESC);
          {
            oprot.writeListBegin(new org.apache.thrift.protocol.TList(org.apache.thrift.protocol.TType.STRING, struct.addresses.size()));
            for (java.lang.String _iter3 : struct.addresses)
            {
              oprot.writeString(_iter3);
            }
            oprot.writeListEnd();
          }
          oprot.writeFieldEnd();
        }
      }
      oprot.writeFieldStop();
      oprot.writeStructEnd();
    }

  }

  private static class PersonTupleSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
    @Override
    public PersonTupleScheme getScheme() {
      return new PersonTupleScheme();
    }
  }

  private static class PersonTupleScheme extends org.apache.thrift.scheme.TupleScheme<Person> {

    @Override
    public void write(org.apache.thrift.protocol.TProtocol prot, Person struct) throws org.apache.thrift.TException {
      org.apache.thrift.protocol.TTupleProtocol oprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
      oprot.writeString(struct.name);
      java.util.BitSet optionals = new java.util.BitSet();
      if (struct.isSetPhone()) {
        optionals.set(0);
      }
      if (struct.isSetAddresses()) {
        optionals.set(1);
      }
      oprot.writeBitSet(optionals, 2);
      if (struct.isSetPhone()) {
        oprot.writeString(struct.phone);
      }
      if (struct.isSetAddresses()) {
        {
          oprot.writeI32(struct.addresses.size());
          for (java.lang.String _iter4 : struct.addresses)
          {
            oprot.writeString(_iter4);
          }
        }
      }
    }

    @Override
    public void read(org.apache.thrift.protocol.TProtocol prot, Person struct) throws org.apache.thrift.TException {
      org.apache.thrift.protocol.TTupleProtocol iprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
      struct.name = iprot.readString();
      struct.setNameIsSet(true);
      java.util.BitSet incoming = iprot.readBitSet(2);
      if (incoming.get(0)) {
        struct.phone = iprot.readString();
        struct.setPhoneIsSet(true);
      }
      if (incoming.get(1)) {
        {
          org.apache.thrift.protocol.TList _list5 = iprot.readListBegin(org.apache.thrift.protocol.TType.STRING);
          struct.addresses = new java.util.ArrayList<java.lang.String>(_list5.size);
          @org.apache.thrift.annotation.Nullable java.lang.String _elem6;
          for (int _i7 = 0; _i7 < _list5.size; ++_i7)
          {
            _elem6 = iprot.readString();
            struct.addresses.add(_elem6);
          }
        }
        struct.setAddressesIsSet(true);
      }
    }
  }

  private static <S extends org.apache.thrift.scheme.IScheme> S scheme(org.apache.thrift.protocol.TProtocol proto) {
    return (org.apache.thrift.scheme.StandardScheme.class.equals(proto.getScheme()) ? STANDARD_SCHEME_FACTORY : TUPLE_SCHEME_FACTORY).getScheme();
  }
}

the somewhat convoluted java.util.stream.Stream.<java.util.Map.Entry<java.lang.String, java.lang.String>>builder() is because in JDK8 there's no vararg map building functions. ideally we can move to https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/Map.html#ofEntries(java.util.Map.Entry...) later