MyEntity.java

@Entity
public class MyEntity {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "id", updatable = false, nullable = false)
	private Long id;

	@Column
	private MyJson jsonProperty;
	
	...
}

myentity.sql

CREATE TABLE myentity
(
  id bigint NOT NULL,
  jsonproperty jsonb,
  CONSTRAINT myentity_pkey PRIMARY KEY (id)
)

MyEntity2.java

@Entity
public class MyEntity {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "id", updatable = false, nullable = false)
	private Long id;

	@Column
	@Type(type = "MyJsonType")
	private MyJson jsonProperty;
	
	...

}

MyJson.java

public class MyJson implements Serializable {

	private String stringProp;
	
	private Long longProp;

	public String getStringProp() {
		return stringProp;
	}

	public void setStringProp(String stringProp) {
		this.stringProp = stringProp;
	}

	public Long getLongProp() {
		return longProp;
	}

	public void setLongProp(Long longProp) {
		this.longProp = longProp;
	}
}

MyJsonType1.java

public class MyJsonType implements UserType {

    @Override
    public int[] sqlTypes() {
        return new int[]{Types.JAVA_OBJECT};
    }

    @Override
    public Class<MyJson> returnedClass() {
        return MyJson.class;
    }
    
    ...
}

MyJsonType2.java

@Override
public Object nullSafeGet(final ResultSet rs, final String[] names, final SessionImplementor session,
                          final Object owner) throws HibernateException, SQLException {
    final String cellContent = rs.getString(names[0]);
    if (cellContent == null) {
        return null;
    }
    try {
        final ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(cellContent.getBytes("UTF-8"), returnedClass());
    } catch (final Exception ex) {
        throw new RuntimeException("Failed to convert String to Invoice: " + ex.getMessage(), ex);
    }
}

@Override
public void nullSafeSet(final PreparedStatement ps, final Object value, final int idx,
                        final SessionImplementor session) throws HibernateException, SQLException {
    if (value == null) {
        ps.setNull(idx, Types.OTHER);
        return;
    }
    try {
        final ObjectMapper mapper = new ObjectMapper();
        final StringWriter w = new StringWriter();
        mapper.writeValue(w, value);
        w.flush();
        ps.setObject(idx, w.toString(), Types.OTHER);
    } catch (final Exception ex) {
        throw new RuntimeException("Failed to convert Invoice to String: " + ex.getMessage(), ex);
    }
}

MyJsonType3.java

@Override
public Object deepCopy(final Object value) throws HibernateException {
	try {
		// use serialization to create a deep copy
    	ByteArrayOutputStream bos = new ByteArrayOutputStream();
    	ObjectOutputStream oos = new ObjectOutputStream(bos);
    	oos.writeObject(value);
    	oos.flush();
    	oos.close();
    	bos.close();
    	
    	ByteArrayInputStream bais = new ByteArrayInputStream(bos.toByteArray());
    	return new ObjectInputStream(bais).readObject();
    } catch (ClassNotFoundException | IOException ex) {
        throw new HibernateException(ex);
    }
}

MyPostgreSQL94Dialect.java

public class MyPostgreSQL94Dialect extends PostgreSQL94Dialect {

	public MyPostgreSQL94Dialect() {
		this.registerColumnType(Types.JAVA_OBJECT, "jsonb");
	}
}

package-info.java

@org.hibernate.annotations.TypeDef(name = "MyJsonType", typeClass = MyJsonType.class)

package org.thoughts.on.java.model;

UseMyEntity.java

MyEntity e = em.find(MyEntity.class, 10000L);
e.getJsonProperty().setStringProp("changed");
e.getJsonProperty().setLongProp(789L);

UseMyEntity2.java

MyEntity e = (MyEntity) em.createNativeQuery("SELECT * FROM myentity e WHERE e.jsonproperty->'longProp' = '456'", MyEntity.class).getSingleResult();