EclipseHelper: ignore .jar file that cannot be found

We recently switched to a more thorough indexing when the EclipseHelper
is called as a main class, including inspecting the Class-Path entry of
the manifest of .jar files. However, said entries might not refer to
existing files, in which case we need to ignore them.

While at it, this fixes the bug that .jar files on the class path would
not have been accessed properly if their paths contained spaces.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

src/main/java/org/scijava/annotations/EclipseHelper.java

@@ -168,12 +168,17 @@ private void maybeIndex(final URL url, final ClassLoader loader) {
 			debug("Not a file URL: " + url);
 			return;
 		}
-		String path = url.getFile();
-		if (!path.startsWith("/")) {
+		File file = FileUtils.urlToFile(url);
+		if (autoDetectEclipse && !file.isAbsolute()) {
 			debug("Not an absolute file URL: " + url);
 			return;
 		}
-		if (path.endsWith(".jar")) {
+		final String name = file.getName();
+		if (name.endsWith(".jar")) {
+			if (!file.isFile()) {
+				debug("Not a file: " + file);
+				return;
+			}
 			/*
 			 * To support mixed development with Eclipse and Maven, let's handle
 			 * the case where Eclipse compiled classes, did not run the annotation
@@ -182,8 +187,8 @@ private void maybeIndex(final URL url, final ClassLoader loader) {
 			 * but crucially also the target/classes/ and target/test-classes/
 			 * directories which may need to be indexed.
 			 */
-			if (!autoDetectEclipse || path.matches(".*/target/surefire/surefirebooter[0-9]*\\.jar")) try {
-				final JarFile jar = new JarFile(path);
+			if (!autoDetectEclipse || url.toString().matches(".*/target/surefire/surefirebooter[0-9]*\\.jar")) try {
+				final JarFile jar = new JarFile(file);
 				Manifest manifest = jar.getManifest();
 				if (manifest != null) {
 					final String classPath =
@@ -205,11 +210,10 @@ private void maybeIndex(final URL url, final ClassLoader loader) {
 			}
 			return;
 		}
-		File directory = FileUtils.urlToFile(url);
-		if (!directory.isDirectory()) {
+		if (!file.isDirectory()) {
 			return;
 		}
-		index(directory, loader);
+		index(file, loader);
 	}
 
 	private void index(File directory, ClassLoader loader) {