@Entity
public class Samples {

    @EmbeddedId
    public SampleId id;


    @MapsId("samplingId")
    @ManyToOne(optional = false)
    private Samplings sampling;

    @OneToOne(mappedBy = "sample", cascade = CascadeType.ALL, fetch = FetchType.LAZY, orphanRemoval = true)
    private TestSamples testSamples;
}

@Entity
public class TestSamples {

    @Id
    @SequenceGenerator(name = "test_samples_id_seq", sequenceName = "test_samples_id_seq", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "test_samples_id_seq")
    private Integer id;

    @OneToOne(fetch = FetchType.LAZY)
    private Samples sample;

    private boolean compression;

    @OneToOne(mappedBy = "testSample", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    private Compressions compressionTest;

    ...
}

select s from Samples s
Join Fetch s.testSamples ts
Left Join Fetch ts.compressionTest ct
Join fetch s.sampling sp
Left Join fetch sp.machine m
Join fetch sp.product p
Join  fetch p.productType pt
where
ts.compressionTest.done=false