Use seed commit as lower changelog boundary for initial commercial releases.

Closes #94

src/main/java/org/springframework/data/release/git/GitOperations.java

@@ -434,10 +434,8 @@ public class GitOperations {
 					.filter(branch -> branch.isIssueBranch(project.getProject().getTracker()))//
 					.collect(Collectors.toMap(Branch::toString, branch -> branch));
 
-			Collection<Ticket> tickets = tracker.findTickets(project,
-					ticketIds.keySet().stream()
-							.map(it -> TicketReference.ofTicket(it, TicketReference.Style.GitHub))
-							.collect(Collectors.toList()));
+			Collection<Ticket> tickets = tracker.findTickets(project, ticketIds.keySet().stream()
+					.map(it -> TicketReference.ofTicket(it, TicketReference.Style.GitHub)).collect(Collectors.toList()));
 
 			return TicketBranches
 					.from(tickets.stream().collect(Collectors.toMap(ticket -> ticketIds.get(ticket.getId()), ticket -> ticket)));
@@ -461,12 +459,17 @@ public class GitOperations {
 			return trainToUse.getIteration(Iteration.GA);
 		}
 
+		Iteration iteration = trainIteration.getIteration();
+		Train train = trainIteration.getTrain();
+		if (iteration.isServiceIteration()) {
+			return train.getIteration(iteration.getPrevious());
+		}
+
 		SupportedProject build = trainIteration.getSupportedProject(Projects.BUILD);
 
 		Optional<TrainIteration> mostRecentBefore = getTags(build) //
-				.filter((tag, ti) -> ti.getTrain().equals(trainIteration.getTrain())) //
-				.find((tag, iteration) -> iteration.getIteration().compareTo(trainIteration.getIteration()) < 0,
-						Pair::getSecond);
+				.filter((tag, ti) -> ti.getTrain().equals(train)) //
+				.find((tag, ti) -> ti.getIteration().compareTo(trainIteration.getIteration()) < 0, Pair::getSecond);
 
 		return mostRecentBefore.orElseThrow(() -> new IllegalStateException(
 				"Cannot determine previous iteration for " + trainIteration.getReleaseTrainNameAndVersion()));
@@ -482,7 +485,7 @@ public class GitOperations {
 			Repository repo = git.getRepository();
 
 			ModuleIteration toModuleIteration = to.getModule(project.getProject());
-			ObjectId fromTag = resolveLowerBoundary(project.getProject(), from, tags, repo);
+			ObjectId fromTag = resolveLowerBoundary(project.getStatus(), project.getProject(), from, tags, git, repo);
 			ObjectId toTag = resolveUpperBoundary(toModuleIteration, tags, repo);
 
 			Iterable<RevCommit> commits = git.log().addRange(fromTag, toTag).call();
@@ -517,15 +520,30 @@ public class GitOperations {
 		return uniqueTicketReferences;
 	}
 
-	protected ObjectId resolveLowerBoundary(Project project, TrainIteration iteration, VersionTags tags, Repository repo)
-			throws IOException {
+	protected ObjectId resolveLowerBoundary(SupportStatus supportStatus, Project project, TrainIteration iteration,
+			VersionTags tags, Git git, Repository repo) throws IOException, GitAPIException {
 
 		if (iteration.contains(project)) {
 
-			Optional<Tag> fromTag = tags.filter(iteration.getTrain()).findTag(iteration.getIteration());
+			Iteration it = iteration.getIteration();
+			Optional<Tag> fromTag = tags.filter(iteration.getTrain()).findTag(it);
 
 			if (!fromTag.isPresent()) {
 
+				// commercial releases might not have a previous tag as commercial releases are seeded without OSS tags.
+				if (supportStatus == SupportStatus.COMMERCIAL && (it.isServiceIteration() || it.isGAIteration())) {
+
+					Branch from = Branch.from(iteration.getModule(project));
+					Iterable<RevCommit> commits = git.log().add(repo.resolve(from.toString())).call();
+
+					Optional<RevCommit> first = Streamable.of(commits).stream()
+							.filter(rev -> rev.getFullMessage().contains("Seed " + from + " branch")).findFirst();
+
+					if (first.isPresent()) {
+						return first.get();
+					}
+				}
+
 				// fall back to main
 				return repo.parseCommit(repo.resolve(Branch.MAIN.toString()));
 			}

src/main/java/org/springframework/data/release/model/Iteration.java

@@ -107,6 +107,10 @@ public class Iteration implements Comparable<Iteration> {
 		return (Iteration) ReflectionUtils.getField(field, null);
 	}
 
+	public static Iteration getServiceRelease(int iterationValue) {
+		return valueOf("SR" + iterationValue);
+	}
+
 	public boolean isGAIteration() {
 		return this.equals(GA);
 	}
@@ -227,4 +231,19 @@ public class Iteration implements Comparable<Iteration> {
 
 		return EQUAL;
 	}
+
+	/**
+	 * Returns the previous iteration for GA or Service Releases.
+	 *
+	 * @return
+	 * @throws IllegalStateException if the current iteration is not a service release.
+	 */
+	public Iteration getPrevious() {
+
+		if (isServiceIteration()) {
+			return getIterationValue() == 1 ? Iteration.GA : Iteration.getServiceRelease(getIterationValue() - 1);
+		}
+
+		throw new IllegalStateException(String.format("Cannot determine previous iteration for %s", this));
+	}
 }

src/test/java/org/springframework/data/release/git/GitOperationsIntegrationTests.java

@@ -100,4 +100,18 @@ class GitOperationsIntegrationTests extends AbstractIntegrationTests {
 		assertThat(hopperSR9.getIteration()).isEqualTo(Iteration.SR9);
 	}
 
+	@Test
+	void shouldDeterminePreviousIterationFromSR() {
+
+		TrainIteration hopperGA = gitOperations.getPreviousIteration(ReleaseTrains.HOPPER.getIteration(Iteration.SR1));
+
+		assertThat(hopperGA.getTrain()).isEqualTo(ReleaseTrains.HOPPER);
+		assertThat(hopperGA.getIteration()).isEqualTo(Iteration.GA);
+
+		TrainIteration hopperSR9 = gitOperations.getPreviousIteration(ReleaseTrains.HOPPER.getIteration(Iteration.SR10));
+
+		assertThat(hopperSR9.getTrain()).isEqualTo(ReleaseTrains.HOPPER);
+		assertThat(hopperSR9.getIteration()).isEqualTo(Iteration.SR9);
+	}
+
 }