Use git.commit.id.abbrev if present

Currently GitProperties always shortens the property git.commit.id to an
hardcoded length of 7.

However, both the Maven plugin git-commit-id-plugin and the Gradle
plugin gradle-git-properties are now providing the property
git.commit.id.abbrev along with the propery git.commit.id.
Moreover, the Maven plugin allows to customize the length of the
abbreviated commit ID with the configuration abbrevLength. The Gradle
plugin doesn't allow (yet) to configure this length.

Closes gh-8773

spring-boot/src/main/java/org/springframework/boot/info/GitProperties.java

@@ -54,6 +54,11 @@ public class GitProperties extends InfoProperties {
 	 * @return the short commit id
 	 */
 	public String getShortCommitId() {
+		String idAbbrev = get("commit.id.abbrev");
+		if (idAbbrev != null) {
+			return idAbbrev;
+		}
+
 		String id = getCommitId();
 		if (id == null) {
 			return null;

spring-boot/src/test/java/org/springframework/boot/info/GitPropertiesTests.java

@@ -32,7 +32,7 @@ public class GitPropertiesTests {
 	@Test
 	public void basicInfo() {
 		GitProperties properties = new GitProperties(
-				createProperties("master", "abcdefghijklmno", "1457527123"));
+				createProperties("master", "abcdefghijklmno", "abcdefg", "1457527123"));
 		assertThat(properties.getBranch()).isEqualTo("master");
 		assertThat(properties.getCommitId()).isEqualTo("abcdefghijklmno");
 		assertThat(properties.getShortCommitId()).isEqualTo("abcdefg");
@@ -50,7 +50,7 @@ public class GitPropertiesTests {
 	@Test
 	public void coerceEpochSecond() {
 		GitProperties properties = new GitProperties(
-				createProperties("master", "abcdefg", "1457527123"));
+				createProperties("master", "abcdefg", null, "1457527123"));
 		assertThat(properties.getCommitTime()).isNotNull();
 		assertThat(properties.get("commit.time")).isEqualTo("1457527123000");
 		assertThat(properties.getCommitTime().getTime()).isEqualTo(1457527123000L);
@@ -59,7 +59,7 @@ public class GitPropertiesTests {
 	@Test
 	public void coerceDateString() {
 		GitProperties properties = new GitProperties(
-				createProperties("master", "abcdefg", "2016-03-04T14:36:33+0100"));
+				createProperties("master", "abcdefg", null, "2016-03-04T14:36:33+0100"));
 		assertThat(properties.getCommitTime()).isNotNull();
 		assertThat(properties.get("commit.time")).isEqualTo("1457098593000");
 		assertThat(properties.getCommitTime().getTime()).isEqualTo(1457098593000L);
@@ -68,24 +68,43 @@ public class GitPropertiesTests {
 	@Test
 	public void coerceUnsupportedFormat() {
 		GitProperties properties = new GitProperties(
-				createProperties("master", "abcdefg", "2016-03-04 15:22:24"));
+				createProperties("master", "abcdefg", null, "2016-03-04 15:22:24"));
 		assertThat(properties.getCommitTime()).isNull();
 		assertThat(properties.get("commit.time")).isEqualTo("2016-03-04 15:22:24");
 	}
 
 	@Test
-	public void shortenCommitId() {
+	public void shortenCommitIdShorterThan7() {
 		GitProperties properties = new GitProperties(
-				createProperties("master", "abc", "1457527123"));
+				createProperties("master", "abc", null, "1457527123"));
 		assertThat(properties.getCommitId()).isEqualTo("abc");
 		assertThat(properties.getShortCommitId()).isEqualTo("abc");
 	}
 
+	@Test
+	public void shortenCommitIdLongerThan7() {
+		GitProperties properties = new GitProperties(
+				createProperties("master", "abcdefghijklmno", null, "1457527123"));
+		assertThat(properties.getCommitId()).isEqualTo("abcdefghijklmno");
+		assertThat(properties.getShortCommitId()).isEqualTo("abcdefg");
+	}
+
+	@Test
+	public void shortCommitIdCustomLength() {
+		GitProperties properties = new GitProperties(
+				createProperties("master", "abcdefghijklmno", "abcdefgh", "1457527123"));
+		assertThat(properties.getCommitId()).isEqualTo("abcdefghijklmno");
+		assertThat(properties.getShortCommitId()).isEqualTo("abcdefgh");
+	}
+
 	private static Properties createProperties(String branch, String commitId,
-			String commitTime) {
+			String commitIdAbbrev, String commitTime) {
 		Properties properties = new Properties();
 		properties.put("branch", branch);
 		properties.put("commit.id", commitId);
+		if (commitIdAbbrev != null) {
+			properties.put("commit.id.abbrev", commitIdAbbrev);
+		}
 		properties.put("commit.time", commitTime);
 		return properties;
 	}