Avoid usueless double calls to rescanLibraries()

Previously rescanLibraries() was automatically called internally in
setLibrariesFolder(). This lead to double calls to rescanLibraries()
when setLibrariesFolder() was used in combination with an explicit
call to rescanLibraries().

This commit adds a new method setLibrariesFoldersAndRescan(..) and
removes the internal call to rescanLibraries() from setLibrariesFolder().

The existing setLibrariesFolder()+rescanLibraries() combos have been
replaced with setLibrariesFoldersAndRescan().

Fix arduino#10228

app/test/cc/arduino/contributions/UpdatableLibraryTest.java

@@ -36,8 +36,7 @@ public void testUpdatableLibrary() throws Exception {
     LibrariesIndexer indexer = new LibrariesIndexer(index_SD_only);
     BaseNoGui.librariesIndexer = indexer;
     indexer.parseIndex();
-    indexer.setLibrariesFolders(folders);
-    indexer.rescanLibraries();
+    indexer.setLibrariesFoldersAndRescan(folders);
 
     ContributedLibrary sdLib = indexer.getIndex().getInstalled("SD").get();
     assertTrue("SD lib is installed", sdLib.isLibraryInstalled());
@@ -46,7 +45,7 @@ public void testUpdatableLibrary() throws Exception {
     assertTrue(ContributionsSelfCheck.checkForUpdatableLibraries());
 
     folders.add(new UserLibraryFolder(SD121, Location.SKETCHBOOK));
-    indexer.setLibrariesFolders(folders);
+    indexer.setLibrariesFoldersAndRescan(folders);
 
     sdLib = indexer.getIndex().getInstalled("SD").get();
     assertTrue("SD lib is installed", sdLib.isLibraryInstalled());
@@ -63,8 +62,7 @@ public void testUpdatableLibraryWithBundled() throws Exception {
     LibrariesIndexer indexer = new LibrariesIndexer(index_Bridge_only);
     BaseNoGui.librariesIndexer = indexer;
     indexer.parseIndex();
-    indexer.setLibrariesFolders(folders);
-    indexer.rescanLibraries();
+    indexer.setLibrariesFoldersAndRescan(folders);
 
     ContributedLibrary l = indexer.getIndex().getInstalled("Bridge").get();
     assertTrue("Bridge lib is installed", l.isLibraryInstalled());
@@ -73,7 +71,7 @@ public void testUpdatableLibraryWithBundled() throws Exception {
     assertTrue(ContributionsSelfCheck.checkForUpdatableLibraries());
 
     folders.add(new UserLibraryFolder(Bridge170, Location.SKETCHBOOK));
-    indexer.setLibrariesFolders(folders);
+    indexer.setLibrariesFoldersAndRescan(folders);
 
     l = indexer.getIndex().getInstalled("Bridge").get();
     assertTrue("Bridge lib is installed", l.isLibraryInstalled());

arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java

@@ -114,7 +114,11 @@ private void parseIndex(File file) throws IOException {
   }
 
   public void setLibrariesFolders(List<UserLibraryFolder> folders) {
-    librariesFolders = folders;
+    this.librariesFolders = folders;
+  }
+
+  public void setLibrariesFoldersAndRescan(List<UserLibraryFolder> folders) {
+    setLibrariesFolders(folders);
     rescanLibraries();
   }