@Retention(value=CLASS) @Target(value=FIELD) public @interface PrimaryKey
RealmPrimaryKeyConstraintException. Primary key cannot be changed after the object created.
Primary keys also count as having the
It is allowed to apply this annotation on the following primitive types: byte, short, int, and long.
String, Byte, Short, Integer, and Long are also allowed, and further permitted to have
as a primary key value.