Add comments and rename variables in PackWriterBitmapPreparer to improve
readability.
Change-Id: I49e7a1c35307298f7bc32ebfc46ab08e94290125
Signed-off-by: Terry Parker <tparker@google.com>
Java compiler must generate synthetic access methods for private methods
and fields of the enclosing class if they are accessed from inner
classes and vice versa.
While invisible in the code, those synthetic access methods exist in the
bytecode and seem to produce some extra execution overhead at runtime
(compared with the direct access to this fields or methods), see
https://git.eclipse.org/r/58948/.
By removing the "private" access modifier from affected methods and
fields we help compiler to avoid generation of synthetic access methods
and hope to improve execution performance.
To validate changes, one can either use javap or use Bytecode Outline
plugin in Eclipse. In both cases one should look for "synthetic
access$<number>" methods at the end of the class and inner class files
in question - there should be none.
NB: don't mix this "synthetic access$" methods up with "public synthetic
bridge" methods generated to allow generic method override return types.
Change-Id: I94fb481b68c84841c1db1a5ebe678b13e13c962b
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Java compiler must generate synthetic access methods for private methods
and fields of the enclosing class if they are accessed from inner
classes and vice versa.
While invisible in the code, those synthetic access methods exist in the
bytecode and seem to produce some extra execution overhead at runtime
(compared with the direct access to this fields or methods), see
https://git.eclipse.org/r/58948/.
By removing the "private" access modifier from affected methods and
fields we help compiler to avoid generation of synthetic access methods
and hope to improve execution performance.
To validate changes, one can either use javap or use Bytecode Outline
plugin in Eclipse. In both cases one should look for "synthetic
access$<number>" methods at the end of the class and inner class files
in question - there should be none.
NB: don't mix this "synthetic access$" methods up with "public synthetic
bridge" methods generated to allow generic method override return types.
Change-Id: Ie7b65f251ec4452d5a5ed48aa0f272cf49a9aecd
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Java compiler must generate synthetic access methods for private methods
and fields of the enclosing class if they are accessed from inner
classes and vice versa.
While invisible in the code, those synthetic access methods exist in the
bytecode and seem to produce some extra execution overhead at runtime
(compared with the direct access to this fields or methods), see
https://git.eclipse.org/r/58948/.
By removing the "private" access modifier from affected methods and
fields we help compiler to avoid generation of synthetic access methods
and hope to improve execution performance.
To validate changes, one can either use javap or use Bytecode Outline
plugin in Eclipse. In both cases one should look for "synthetic
access$<number>" methods at the end of the class and inner class files
in question - there should be none.
NB: don't mix this "synthetic access$" methods up with "public synthetic
bridge" methods generated to allow generic method override return types.
Change-Id: I0ebaeb2bc454cd8051b901addb102c1a6688688b
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Java compiler must generate synthetic access methods for private methods
and fields of the enclosing class if they are accessed from inner
classes and vice versa.
While invisible in the code, those synthetic access methods exist in the
bytecode and seem to produce some extra execution overhead at runtime
(compared with the direct access to this fields or methods), see
https://git.eclipse.org/r/58948/.
By removing the "private" access modifier from affected methods and
fields we help compiler to avoid generation of synthetic access methods
and hope to improve execution performance.
To validate changes, one can either use javap or use Bytecode Outline
plugin in Eclipse. In both cases one should look for "synthetic
access$<number>" methods at the end of the class and inner class files
in question - there should be none.
NB: don't mix this "synthetic access$" methods up with "public synthetic
bridge" methods generated to allow generic method override return types.
Change-Id: If53ec94145bae47b74e2561305afe6098012715c
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Expose the following bitmap selection parameters via PackConfig:
"bitmapContiguousCommitCount", "bitmapRecentCommitCount",
"bitmapRecentCommitSpan", "bitmapDistantCommitSpan",
"bitmapExcessiveBranchCount", and "bitmapInactiveBranchAge".
The value of bitmapContiguousCommitCount, whereby bitmaps are
created for the most recent N commits in a branch, has never
been verified. If experiments show that they are not valuable,
then we can simplify the implementation so that there is only
a concept of recent and distant commit history (defined by
"bitmapRecentCommitCount"), and the only controls we need are
"bitmapRecentCommitSpan" and "bitmapDistantCommitSpan".
Change-Id: I288bf3f97d6fbfdfcd5dde2699eff433a7307fb9
Signed-off-by: Terry Parker <tparker@google.com>
Replace the “bitmapCommitRange” parameter that was recently introduced
with two new parameters: “bitmapExcessiveBranchCount” and
“bitmapInactiveBranchAgeInDays”. If the count of branches does not
exceed “bitmapExcessiveBranchCount”, then the current algorithm is kept
for all branches.
If the branch count is excessive, then the commit time for the tip
commit for each branch is used to determine if a branch is “inactive”.
"Active" branches get full commit selection using the existing
algorithm. "Inactive" branches get fewer bitmaps near the branch tips.
Introduce a "contiguousCommitCount" parameter that always enforces that
the N most recent commits in a branch are selected for bitmaps. The
previous nextSelectionDistance() algorithm created anywhere from 1-100
contiguous bitmaps at branch tips.
For example, consider a branch with commits numbering 0-300, with 0
being the most recent commit. If the most recent 200 commits are not
merge commits and the 200th commit was the last one selected,
nextSelectionDistance() returned 100, causing commits 200-101 to be
ignored. Then a window of size 100 was evaluated, searching for merge
commits. Since no merge commits are found, the next commit (commit 0)
was selected, for a total of 1 commit in the topmost 100 commits.
If instead the 250th commit was selected, then by the same logic
commit 50 is selected. At that point nextSelectionDistance() switches to
selecting consecutive commits, so commits 0-50 in the topmost 100
commits are selected. The "contiguousCommitCount" parameter provides
more determinism by always selecting a constant number or topmost
commits.
Add an optimization to break out of the inner loop of selectCommits() if
all of the commits for the current branch have already been found.
When reusing bitmaps from an existing pack, remove unnecessary
populating and clearing of the writeBitmaps/PackBitmapIndexBuilder.
Add comments to PackWriterBitmapPreparer, rename methods and variables
for readability.
Add tests for bitmap selection with and without merge commits and with
excessive branch pruning triggered.
Note: I will follow up with an additional change that exposes the new
parameters through PackConfig.
Change-Id: I5ccbb96c8849f331c302d9f7840e05f9650c4608
Signed-off-by: Terry Parker <tparker@google.com>
Since Git 2.6 wildcard restrictions for refspecs have been loosened:
refspecs like "refs/heads/*foo:refs/heads/foo*" are valid now.
See Git commit 8d3981ccbed9fc211b4e67105015179d9d2a5692
Change-Id: Icb78afbd282c425173b3a7bc10eadc4015689bb8
Signed-off-by: Marc Strapetz <marc.strapetz@syntevo.com>
Building on top of https://git.eclipse.org/r/#/c/56391/
Here we preserve compatibility with JetS3t
and add 2 new native JGit encryption implementations.
For reference, see connection configuration files:
* Version 0: jgit-s3-connection-v-0.properties
* Version 1: jgit-s3-connection-v-1.properties
* Version 2: jgit-s3-connection-v-2.properties
Change-Id: I713290bcacbe92d88e5ef28ce137de73dd1abe2f
Signed-off-by: Andrei Pozolotin <andrei.pozolotin@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
See previous attempt: https://git.eclipse.org/r/#/c/16674/
Here we preserve as much of JetS3t mode as possible
while allowing to use new Java 8+ PBE algorithms
such as PBEWithHmacSHA512AndAES_256
Summary of changes:
* change pom.xml to control long tests
* add WalkEncryptionTest.launch to run long tests
* add AmazonS3.Keys to to normalize use of constants
* change WalkEncryption to support AES in JetS3t mode
* add WalkEncryptionTest to test remote encryption pipeline
* add support for CI configuration for live Amazon S3 testing
* add log4j based logging for tests in both Eclipse and Maven build
To test locally, check out the review branch, then:
* create amazon test configuration file
* located your home dir: ${user.home}
* named jgit-s3-config.properties
* file format follows AmazonS3 connection settings file:
accesskey = your-amazon-access-key
secretkey = your-amazon-secret-key
test.bucket = your-bucket-for-testing
* finally:
* run in Eclipse: WalkEncryptionTest.launch
* or
* run in Shell: mvn test --define test=WalkEncryptionTest
Change-Id: I6f455fd9fb4eac261ca73d0bec6a4e7dae9f2e91
Signed-off-by: Andrei Pozolotin <andrei.pozolotin@gmail.com>
If the checkout path is currently a non-empty directory (and was a link
or a regular file before), this directory will be removed before
performing checkout, but only if the checkout path is specified.
Bug: 474973
Change-Id: Ifc6c61592d9b54d26c66367163acdebea369145c
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
A bitmap index contains bitmaps for a set of commits in a pack file.
Creating a bitmap for every commit is too expensive, so heuristics
select the most "important" commits. The most recent commits are the
most valuable. To clone a repository only those for the branch tips are
needed. When fetching, only commits since the last fetch are needed.
The commit selection heuristics generally work, but for some
repositories the number of selected commits is prohibitively high. One
example is the MSM 3.10 Linux kernel. With over 1 million commits on
2820 branches, the current heuristics resulted in +36k selected commits.
Each uncompressed bitmap for that repository is ~413k, making it
difficult to complete a GC operation in available memory.
The benefit of creating bitmaps over the entire history of a repository
like the MSM 3.10 Linux kernel isn't clear. For that repository, most
history for the last year appears to be in the last 100k commits.
Limiting bitmap commit selection to just those commits reduces the count
of selected commits from ~36k to ~10.5k. Dropping bitmaps for older
commits does not affect object counting times for clones or for fetches
on clients that are reasonably up-to-date.
This patch defines a new "bitmapCommitRange" PackConfig parameter to
limit the commit selection process when building bitmaps. The range
starts with the most recent commit and walks backwards. A range of 10k
considers only the 10000 most recent commits. A range of zero creates
bitmaps only for branch tips. A range of -1 (the default) does not limit
the range--all commits in the pack are used in the commit selection
process.
Change-Id: Ied92c70cfa0778facc670e0f14a0980bed5e3bfb
Signed-off-by: Terry Parker <tparker@google.com>
On a server also running Gerrit that is using RepoCommand to
convert from an XML manifest to a git submodule superproject
periodically, it would be handy to be able to use Gerrit's
submodule subscription feature[1] to update the superproject
automatically between RepoCommand runs as changes are merged
in each subprojects.
This requires setting the 'branch' field for each submodule
so that Gerrit knows what branch to watch. Add an option to
do that.
Setting the branch field also is useful for plain Git users,
since it allows them to use "git submodule update --remote" to
manually update all submodules between RepoCommand runs.
[1] https://gerrit-review.googlesource.com/Documentation/user-submodules.html
Change-Id: I1a10861bcd0df3b3673fc2d481c8129b2bdac5f9
Signed-off-by: Stefan Beller <sbeller@google.com>
Clirr doesn't support Java 8 hence use japicmp instead.
See https://github.com/siom79/japicmp
Change-Id: If4b30a6d6aa849b4d6b3b0c900558c609822840c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
This patch makes JGit parsing of ignore rules containing unmatched '['
bracket compatible to the Git CLI.
Since '[' starts character group, Git tries to parse the ignore rule as
a shell glob pattern and if the character group is not closed, the glob
pattern is invalid and so the ignore rule never matches anything.
See also http://article.gmane.org/gmane.comp.version-control.git/278699.
Bug: 478490
Change-Id: I734a4d14fcdd721070e3f75d57e33c2c0700d503
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
- Remove declaration of IOException that is no longer thrown
- Add missing //$NON-NLS-1$ to prevent "Non-externalized string literal"
warning.
These warnings seem to have been introduced by If13f7b406.
Change-Id: I30058eed31b92067a6ab22e787732b08e29f8d63
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>
Since 4.0 we require Java 7 so there is no longer a need to override the
following methods in FS_POSIX, FS_Win32, FS_Win32_Cygwin
- lastModified()
- setLastModified()
- length()
- isSymlink()
- exists()
- isDirectory()
- isFile()
- isHidden()
Hence implement these methods in FS and remove overrides in subclasses.
Change-Id: I5dbde6ec806c66c86ac542978918361461021294
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
As discussed on https://git.eclipse.org/r/53836 it does not make sense
to have two similar utility classes in same package with intersecting
functionality. To not break the API, all methods from FileUtil are
copied to FileUtils, all FileUtil API is made deprecated and redirecting
now to FileUtils. Moved simple methods which are available in Java 7 API
are made package private and can be removed at any point later entirely
(right now they are in use).
Bug: 475070
Change-Id: Idffcf9840496c448173af7c052d8898ada68e27b
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
SystemReader.isMacOs() and SystemReader.isWindows() return values are
unlikely to change during the JVM lifetime (except tests). Don't read
system properties each time the methods are called, just use previously
calculated value.
Change-Id: I495521f67a8b544e7b7247d99bbd05a42ea16d20
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
An attempt to re-implement not well documented Git CLI behavior for
patterns with backslashes.
It looks like Git silently ignores all \ characters in ignore rules, if
they are NOT covered by 3 cases described in [1]:
{quote}
1) ... Put a backslash ("\") in front of the first hash for patterns
that begin with a hash.
...
2) Trailing spaces are ignored unless they are quoted with backslash
("\").
...
3) Put a backslash ("\") in front of the first "!" for patterns that
begin with a literal "!", for example, "\!important!.txt".
{quote}
Undocumented also is the fact that backslash itself can be escaped by
backslash.
So \h\e\l\l\o\.t\x\t rule matches hello.txt and a\\\\b a\b in Git CLI.
Additionally, the glob parser [2] knows special meaning of backslash:
{quote}
One can remove the special meaning of '?', '*' and '[' by preceding
them by a backslash, or, in case this is part of a shell command
line, enclosing them in quotes. Between brackets these characters
stand for themselves. Thus, "[[?*\]" matches the four characters
'[', '?', '*' and '\'.
{quote}
[1] https://www.kernel.org/pub/software/scm/git/docs/gitignore.html
[2] http://man7.org/linux/man-pages/man7/glob.7.html
Bug: 478065
Change-Id: I3dc973475d1943c5622103701fa8cb3ea0684e3e
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Currently we fail to properly recognize character group if the pattern
before character group contains opening bracket.
See comment from Sebastien Arod on https://git.eclipse.org/r/56678/
Change-Id: I70d3657a2a328818ea2bdc1409d18ecb3a85825b
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Current DiffFormat behavior regarding submodules (aka git links) is
incorrect. The "Subproject commit <sha1>" appears as part of the diff
header, rather than as its own hunk.
--> From JGit implementation
diff --git a/plugins/cookbook-plugin b/plugins/cookbook-plugin
index b9d3ca8..ec6ed89 160000
--- a/plugins/cookbook-plugin
+++ b/plugins/cookbook-plugin
-Subproject commit b9d3ca8a65030071e28be19296ba867ab424fbbf
+Subproject commit ec6ed89c47ba7223f82d9cb512926a6c5081343e
--> From C Git 2.5.2
diff --git a/plugins/cookbook-plugin b/plugins/cookbook-plugin
index b9d3ca8..ec6ed89 160000
--- a/plugins/cookbook-plugin
+++ b/plugins/cookbook-plugin
@@ -1 +1 @@
-Subproject commit b9d3ca8a65030071e28be19296ba867ab424fbbf
+Subproject commit ec6ed89c47ba7223f82d9cb512926a6c5081343e
The current way of processing submodules results in no hunk header and
includes the contents of the hunk as part of the headers. To fix this, we
can't just have our writeGitLinkDiffText output the hunk header. We have
to change the flow so that the raw text gets parsed as a diff. The easiest
way to do this is to fake the RawText in the FormatResult when we have a
GITLINK.
It should be noted that it seems possible for there to be a difference
between a GITLINK and a non-GITLINK, but I don't think this can happen in
practice, so I don't think we need to worry too much about it.
This patch also fixes up the test for GitLink headers, as the test was
for the old behavior. My setup has 3 other failing tests which may or
may not be the result of environmental changes. However, the same tests
fail without this commit, so I do not believe they are related.
Bug: 477759
Change-Id: If13f7b406904fad814416c93ed09ea47ef183337
Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Ignore rules should escape $^(){}+| chars if using regular expressions,
because they should be treated literally if they aren't part of a
character group.
Bug: 478055
Change-Id: Ic7276442d7f8f02594b85eae1ef697362e62d3bd
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
If a client mistakenly tries to send a tag object as a shallow line
JGit blindly assumes this is a commit and tries to parse the tag
buffer using the commit parser. This can cause an obtuse error like:
InvalidObjectIdException: Invalid id: t c0ff331234...
The "t" comes from the "object c0ff331234..." line of the tag tring
to be parsed as though it where the "tree" line of a commit.
Run any client supplied shallow lines through the RevWalk to lookup
the object types. Fail fast with a protocol exception if any of them
are non-commit.
Skip objects not known to this repository. This matches behavior
with git-core's upload-pack, which sliently skips over any shallow
line object named by the client but not known by the server.
Change-Id: Ic6c57a90a42813164ce65c2244705fc42e84d700
Properties.containsKey() is the correct call here; contains() was testing
if a value is present but the key is what was meant.
Change-Id: Ice72c9f4388583e18cf8aca6e837cc4299fd07fd
When we have a URI that contains an empty path component (that is
it only contains a "/") we want to fall back to the host as
humanish name.
This change is according to the behavior of upstream git, which
falls back on the hostname when guessing directory names for
newly cloned repositories (see [1] for the discussion).
[1] http://article.gmane.org/gmane.comp.version-control.git/274669
Change-Id: I44400c6ab72a2722d2155d53d63671bd867d6c44
Signed-off-by: Patrick Steinhardt <ps@pks.im>
If no refs match the input list and we are writing to a batch,
the returned new commit from write() will match the current commit.
Adding a command to the batch for this case is harmless as it will
succeed, but it's more straightforward to just skip adding a command
in this case.
Add tests or the combination of saving matching refs and saving to a
batch.
Change-Id: I6837389b08e6c80bc2d4c9e9c506d07293ea5fb2
This header was removed unintentionally from some bundles in
3a4a5a4e57. Restore it to ensure lazy
activation of bundles.
Change-Id: I1f841f978fb93278e3ec0533a01f1363510dd976
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
In Bug 476164 it was reported that EGit doesn't start when the platform
comes with jsch 0.1.51 while this version of EGit/JGit brings jsch
0.1.53. This could be caused by outdated uses-clauses. Hence recompute
them using PDE tooling.
Bug: 476164
Change-Id: I185ba097884ead9cd034eba842bd3bf34181a99b
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
It was reported in [1] that 197e3393a5 led
to a performance regression in a BFG benchmark. Analysis showed that
this is caused by the exists() method in FS_POSIX, now overriding the
default implementation in FS. The default implementation of FS.exists()
uses java.io.File.exists(), while the new implementation in FS_POSIX
uses java.nio.file.Files.exists() - by simply removing the override in
FS_POSIX, performance was restored.
Profiling showed that java.nio.file.Files.exists() is substantially
slower than java.io.File.exists(), to the point where the exists() call
doubles the average cost of a call to
ObjectDirectory.insertUnpackedObject() - which the BFG uses a lot,
because it's rewriting history. Average times measured on Ubuntu were:
java.io.File.exists() - 4 microseconds
java.nio.file.Files.exists() - 60 microseconds
The loose object exists test should be using java.io.File and not FS.
ObjectDirectory uses FS.resolve() to traverse symlinks to objects but
then once inside objects all 256 sharded directories should be real
directories, and the object files should be real files, not dangling
symlinks. java.io.File.exists() is sufficient here, and faster.
Change ObjectDirectory to use File.exists() once its computed the File
handle.
This does mean JGit cannot run ObjectDirectory code on an abstract
virtual filesystem plugged into NIO2. If you really want to run JGit on
an esoteric non-standard filesystem like "in memory" you should look at
the DFS storage backend, which has fewer abstraction points to deal
with. Or write your own from scratch.
[1] https://dev.eclipse.org/mhonarc/lists/jgit-dev/msg02954.html
Change-Id: I74684dc3957ae1ca52a7097f83a6c420aa24310f
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
- add @since annotation for new API method
- silence non-externalized String warning
Change-Id: I864176ced64e9569e7f2cdf8f777720655bfc578
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
On a local filesystem the packed-refs file will be orphaned if it is
replaced by another client while the current client is reading the old
one. However, since NFS servers do not keep track of open files, instead
of orphaning the old packed-refs file, such a replacement will cause the
old file to be garbage collected instead. A stale file handle exception
will be raised on NFS servers if the file is garbage collected (deleted)
on the server while it is being read. Since we no longer have access to
the old file in these cases, the previous code would just fail. However,
in these cases, reopening the file and rereading it will succeed (since
it will reopen the new replacement file). So retrying the read is a
viable strategy to deal with stale file handles on the packed-refs file,
implement such a strategy.
Since it is possible that the packed-refs file could be replaced again
while rereading it (multiple consecutive updates can easily occur with
ref deletions), loop on stale file handle exceptions, up to 5 extra
times, trying to read the packed-refs file again, until we either read
the new file, or find that the file no longer exists. The limit of 5 is
arbitrary, and provides a safe upper bounds to prevent infinite loops
consuming resources in a potential unforeseen persistent error
condition.
Change-Id: I085c472bafa6e2f32f610a33ddc8368bb4ab1814
Signed-off-by: Martin Fick<mfick@codeaurora.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Add a public API to the FileUtils to determine if an IOException is a
stale NFS file handle exception. This will make it easier to detect
such errors, and interpret them consistently throughout the codebase.
This new API is a bit more lenient in its detection than the previous
detection, and should be able to detect some errors which previously
were not identified as stale file handle exceptions because they had the
word NFS in the error message. Adjust the packfile handling code to use
this new API for detection.
Change-Id: I21f80014546ba1afec7335890e5ae79e7f521412
Signed-off-by: Martin Fick<mfick@codeaurora.org>
Signaling the need to flush() only via the interrupted status of a
copying thread doesn't work realiably with jsch. The write() method of
com.jcraft.jsch.Session catches the InterruptedException in several
places. As a result StreamCopyThread can easily miss the interrupt if it
was interrupted during the dst.write() or dst.flush() call. When it
happens, StreamCopyThread will not send some data to the remote side and
will not get the response back, because remote side will wait for more
data from us.
The flushCount field incremented during flush() method guarantees we
don't miss flush() even if jsch catches InterruptedException in
dst.write() or dst.flush() calls.
Checking the flushCount after dst.write() is needed because dst.write()
can clear interrupt status, in this case the next blocking src.read()
won't throw an exception and we will not call flush().
Flush is performed only after src.read() was blocked and thrown an
InterruptedIOException exception, this guarantees that we flush all the
data available in src so far (src.read() doesn't block while more is
available).
FlushCount is reset to 0 only when there were no flush() calls since
last blocked read, that means we flushed all data available in src. If
there were flush() calls, the interrupt status is restored, so next
blocked read will throw InterruptedException and we will flush()
again.
Change-Id: I692b226edaff502f06235ec05da9052b5fe6478a
Signed-off-by: Dmitry Neverov <dmitry.neverov@gmail.com>
There should be no functional change, the logic updated only to make
code simple so that compiler can understand what is going for. Removed
all @SuppressWarnings("null") annotations since they cannot be used if
"org.eclipse.jdt.core.compiler.problem.potentialNullReference" option is
set to the "error" level.
Bug: 470647
Change-Id: Ie93c249fa46e792198d362e531d5cbabaf41fdc4
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>