Add failing testcases for wrong order in batch save and possible fix for one of them

ebean-test/src/test/java/io/ebeaninternal/server/transaction/TransactionTest.java

@@ -0,0 +1,70 @@
+package io.ebeaninternal.server.transaction;
+
+import io.ebean.*;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.tests.model.basic.relates.*;
+
+public class TransactionTest extends BaseTestCase {
+  private Relation1 r1 = new Relation1("R1");
+  private Relation2 r2 = new Relation2("R2");
+  private Relation3 r3 = new Relation3("R3");
+
+  private Transaction txn;
+
+  @BeforeEach
+  void beginTransaction() {
+    txn = DB.beginTransaction();
+    txn.setBatchMode(true);
+  }
+
+  @AfterEach
+  void commitTransaction() {
+    txn.commit();
+    txn.close();
+  }
+
+  @Test
+  public void testMultiSave1() {
+    r2.setWithCascade(r3);
+    r1.setWithCascade(r2);
+    DB.save(r1);
+  }
+
+  @Test
+  public void testMultiSave2() {
+    r2.setWithCascade(r3);
+    r1.setWithCascade(r2);
+    DB.save(r3);
+    DB.save(r1);
+  }
+
+  @Test
+  public void testMultiSave3() {
+    r2.setWithCascade(r3);
+    r1.setWithCascade(r2);
+    DB.save(r3);
+    DB.save(r2);
+    DB.save(r1);
+  }
+
+  @Test
+  public void testMultiSave4() {
+    r2.setNoCascade(r3);
+    r1.setWithCascade(r2);
+    DB.save(r3);
+    // Workaround: txn.flush();
+    DB.save(r1);
+  }
+
+  @Test
+  public void testMultiSave5() {
+    r2.setNoCascade(r3);
+    r1.setNoCascade(r2);
+    DB.save(r3);
+    DB.save(r2);
+    DB.save(r1);
+  }
+}

ebean-test/src/test/java/org/tests/model/basic/relates/Relation1.java

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+package org.tests.model.basic.relates;
+
+
+import java.util.UUID;
+
+import javax.persistence.*;
+
+import io.ebean.annotation.ChangeLog;
+
+/**
+ * Relation entity
+ */
+@Entity
+@ChangeLog
+public class Relation1 {
+
+  @Id
+  private UUID id = UUID.randomUUID();
+
+  private String name;
+
+  public Relation1(String name) {
+    this.name = name;
+  }
+
+  @ManyToOne
+  private Relation2 noCascade;
+
+  @ManyToOne(cascade = CascadeType.ALL)
+  private Relation2 withCascade;
+
+  public UUID getId() {
+    return id;
+  }
+
+  public void setId(UUID id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public Relation2 getNoCascade() {
+    return noCascade;
+  }
+
+  public void setNoCascade(Relation2 noCascade) {
+    this.noCascade = noCascade;
+  }
+
+  public Relation2 getWithCascade() {
+    return withCascade;
+  }
+
+  public void setWithCascade(Relation2 withCascade) {
+    this.withCascade = withCascade;
+  }
+  
+}

ebean-test/src/test/java/org/tests/model/basic/relates/Relation2.java

@@ -0,0 +1,64 @@
+package org.tests.model.basic.relates;
+
+
+import java.util.UUID;
+
+import javax.persistence.*;
+
+import io.ebean.annotation.ChangeLog;
+
+/**
+ * Relation entity
+ */
+@Entity
+@ChangeLog
+public class Relation2 {
+
+  @Id
+  private UUID id = UUID.randomUUID();
+
+  private String name;
+
+  public Relation2(String name) {
+    this.name = name;
+  }
+
+  @ManyToOne
+  private Relation3 noCascade;
+
+  @ManyToOne(cascade = CascadeType.ALL)
+  private Relation3 withCascade;
+
+  public UUID getId() {
+    return id;
+  }
+
+  public void setId(UUID id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public Relation3 getNoCascade() {
+    return noCascade;
+  }
+
+  public void setNoCascade(Relation3 noCascade) {
+    this.noCascade = noCascade;
+  }
+
+  public Relation3 getWithCascade() {
+    return withCascade;
+  }
+
+  public void setWithCascade(Relation3 withCascade) {
+    this.withCascade = withCascade;
+  }
+  
+}

ebean-test/src/test/java/org/tests/model/basic/relates/Relation3.java

@@ -0,0 +1,42 @@
+package org.tests.model.basic.relates;
+
+
+import java.util.UUID;
+
+import javax.persistence.*;
+
+import io.ebean.annotation.ChangeLog;
+
+/**
+ * Relation entity
+ */
+@Entity
+@ChangeLog
+public class Relation3 {
+
+  @Id
+  private UUID id = UUID.randomUUID();
+
+  private String name;
+
+  public Relation3(String name) {
+    this.name = name;
+  }
+
+  public UUID getId() {
+    return id;
+  }
+
+  public void setId(UUID id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+}