hollow/src/main/java/com/netflix/hollow/core/write/objectmapper/HollowObjectMapper.java
public RecordPrimaryKey extractPrimaryKey(Object o) {
        HollowObjectTypeMapper typeMapper = (HollowObjectTypeMapper) getTypeMapper(o.getClass(), null, null);
        return new RecordPrimaryKey(typeMapper.getTypeName(), typeMapper.extractPrimaryKey(o));
    }
public RecordPrimaryKey extractPrimaryKey(Object o) {
        HollowObjectTypeMapper typeMapper = (HollowObjectTypeMapper) getTypeMapper(o.getClass(), null, null);
        return new RecordPrimaryKey(typeMapper.getTypeName(), typeMapper.extractPrimaryKey(o));
    }
Extracts the primary key from the specified POJO.

@param o the POJO
@return the primary key
@throws IllegalArgumentException if the POJO does not have primary key defined