Fix missing jar entry certificates

Ensure that the source jar entry is closed before reading
certificates and code signers from the entry.

gh-19041

Author: philwebb

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFileEntries.java

@@ -353,11 +353,12 @@ JarEntryCertification getCertification(JarEntry entry) throws IOException {
 			try (JarInputStream certifiedJarStream = new JarInputStream(this.jarFile.getData().getInputStream())) {
 				java.util.jar.JarEntry certifiedEntry = null;
 				while ((certifiedEntry = certifiedJarStream.getNextJarEntry()) != null) {
+					// Entry must be closed to trigger a read and set entry certificates
+					certifiedJarStream.closeEntry();
 					int index = getEntryIndex(certifiedEntry.getName());
 					if (index != -1) {
 						certifications[index] = JarEntryCertification.from(certifiedEntry);
 					}
-					certifiedJarStream.closeEntry();
 				}
 			}
 			this.certifications = certifications;

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java

@@ -385,10 +385,13 @@ public void verifySignedJar() throws Exception {
 				while (actualEntries.hasMoreElements()) {
 					JarEntry actualEntry = actualEntries.nextElement();
 					java.util.jar.JarEntry expectedEntry = expected.getJarEntry(actualEntry.getName());
-					assertThat(actualEntry.getCertificates()).as(actualEntry.getName())
-							.isEqualTo(expectedEntry.getCertificates());
-					assertThat(actualEntry.getCodeSigners()).as(actualEntry.getName())
-							.isEqualTo(expectedEntry.getCodeSigners());
+					StreamUtils.drain(expected.getInputStream(expectedEntry));
+					if (!actualEntry.getName().equals("META-INF/MANIFEST.MF")) {
+						assertThat(actualEntry.getCertificates()).as(actualEntry.getName())
+								.isEqualTo(expectedEntry.getCertificates());
+						assertThat(actualEntry.getCodeSigners()).as(actualEntry.getName())
+								.isEqualTo(expectedEntry.getCodeSigners());
+					}
 				}
 				assertThat(stopWatch.getTotalTimeSeconds()).isLessThan(3.0);
 			}