* Add string comparison methods to StringUtils, fix dictionary comparisons.
There are various places in Druid code where we assume that String.compareTo
is consistent with Unicode code-point ordering. Sadly this is not the case.
To help deal with this, this patch introduces the following helpers:
1) compareUnicode: Compares two Strings in Unicode code-point order.
2) compareUtf8: Compares two UTF-8 byte arrays in Unicode code-point order.
Equivalent to comparison as unsigned bytes.
3) compareUtf8UsingJavaStringOrdering: Compares two UTF-8 byte arrays, or
ByteBuffers, in a manner consistent with String.compareTo.
There is no helper for comparing two Strings in a manner consistent
with String.compareTo, because for that we can use compareTo directly.
The patch also fixes an inconsistency between the String and UTF-8
dictionary GenericIndexed flavors of string-typed columns: they were
formerly using incompatible comparators.
* Adjust test.
* FrontCodedIndexed updates.
* Add test.
* Fix comments.
* Always return sketches from DS_HLL, DS_THETA, DS_QUANTILES_SKETCH.
These aggregation functions are documented as creating sketches. However,
they are planned into native aggregators that include finalization logic
to convert the sketch to a number of some sort. This creates an
inconsistency: the functions sometimes return sketches, and sometimes
return numbers, depending on where they lie in the native query plan.
This patch changes these SQL aggregators to _never_ finalize, by using
the "shouldFinalize" feature of the native aggregators. It already
existed for theta sketches. This patch adds the feature for hll and
quantiles sketches.
As to impact, Druid finalizes aggregators in two cases:
- When they appear in the outer level of a query (not a subquery).
- When they are used as input to an expression or finalizing-field-access
post-aggregator (not any other kind of post-aggregator).
With this patch, the functions will no longer be finalized in these cases.
The second item is not likely to matter much. The SQL functions all declare
return type OTHER, which would be usable as an input to any other function
that makes sense and that would be planned into an expression.
So, the main effect of this patch is the first item. To provide backwards
compatibility with anyone that was depending on the old behavior, the
patch adds a "sqlFinalizeOuterSketches" query context parameter that
restores the old behavior.
Other changes:
1) Move various argument-checking logic from runtime to planning time in
DoublesSketchListArgBaseOperatorConversion, by adding an OperandTypeChecker.
2) Add various JsonIgnores to the sketches to simplify their JSON representations.
3) Allow chaining of ExpressionPostAggregators and other PostAggregators
in the SQL layer.
4) Avoid unnecessary FieldAccessPostAggregator wrapping in the SQL layer,
now that expressions can operate on complex inputs.
5) Adjust return type to thetaSketch (instead of OTHER) in
ThetaSketchSetBaseOperatorConversion.
* Fix benchmark class.
* Fix compilation error.
* Fix ThetaSketchSqlAggregatorTest.
* Hopefully fix ITAutoCompactionTest.
* Adjustment to ITAutoCompactionTest.
In clusters with a large number of segments, the duty `MarkAsUnusedOvershadowedSegments`
can take a long very long time to finish. This is because of the costly invocation of
`timeline.isOvershadowed` which is done for every used segment in every coordinator run.
Changes
- Use `DataSourceSnapshot.getOvershadowedSegments` to get all overshadowed segments
- Iterate over this set instead of all used segments to identify segments that can be marked as unused
- Mark segments as unused in the DB in batches rather than one at a time
- Refactor: Add class `SegmentTimeline` for ease of use and readability while using a
`VersionedIntervalTimeline` of segments.
* introduce a "tree" type to the flattenSpec
* feedback - rename exprs to nodes, use CollectionsUtils.isNullOrEmpty for guard
* feedback - expand docs to more clearly capture limitations of "tree" flattenSpec
* feedback - fix for typo on docs
* introduce a comment to explain defensive copy, tweak null handling
* fix: part of rebase
* mark ObjectFlatteners.FlattenerMaker as an ExtensionPoint and provide default for new tree type
* fix: objectflattener restore previous behavior to call getRootField for root type
* docs: ingestion/data-formats add note that ORC only supports path expressions
* chore: linter remove unused import
* fix: use correct newer form for empty DimensionsSpec in FlattenJSONBenchmark
* First set of changes for framework
* Second set of changes to move segment map function to data source
* Minot change to server manager
* Removing the createSegmentMapFunction from JoinableFactoryWrapper and moving to JoinDataSource
* Checkstyle fixes
* Patching Eric's fix for injection
* Checkstyle and fixing some CI issues
* Fixing code inspections and some failed tests and one injector for test in avatica
* Another set of changes for CI...almost there
* Equals and hashcode part update
* Fixing injector from Eric + refactoring for broadcastJoinHelper
* Updating second injector. Might revert later if better way found
* Fixing guice issue in JoinableFactory
* Addressing review comments part 1
* Temp changes refactoring
* Revert "Temp changes refactoring"
This reverts commit 9da42a9ef0.
* temp
* Temp discussions
* Refactoring temp
* Refatoring the query rewrite to refer to a datasource
* Refactoring getCacheKey by moving it inside data source
* Nullable annotation check in injector
* Addressing some comments, removing 2 analysis.isJoin() checks and correcting the benchmark files
* Minor changes for refactoring
* Addressing reviews part 1
* Refactoring part 2 with new test cases for broadcast join
* Set for nullables
* removing instance of checks
* Storing nullables in guice to avoid checking on reruns
* Fixing a test case and removing an irrelevant line
* Addressing the atomic reference review comments
* add FrontCodedIndexed for delta string encoding
* now for actual segments
* fix indexOf
* fixes and thread safety
* add bucket size 4, which seems generally better
* fixes
* fixes maybe
* update indexes to latest interfaces
* utf8 support
* adjust
* oops
* oops
* refactor, better, faster
* more test
* fixes
* revert
* adjustments
* fix prefixing
* more chill
* sql nested benchmark too
* refactor
* more comments and javadocs
* better get
* remove base class
* fix
* hot rod
* adjust comments
* faster still
* minor adjustments
* spatial index support
* spotbugs
* add isSorted to Indexed to strengthen indexOf contract if set, improve javadocs, add docs
* fix docs
* push into constructor
* use base buffer instead of copy
* oops
* Refactor Calcite test "framework" for planner tests
Refactors the current Calcite tests to make it a bit easier
to adjust the set of runtime objects used within a test.
* Move data creation out of CalciteTests into TestDataBuilder
* Move "framework" creation out of CalciteTests into
a QueryFramework
* Move injector-dependent functions from CalciteTests
into QueryFrameworkUtils
* Wrapper around the planner factory, etc. to allow
customization.
* Bulk of the "framework" created once per class rather
than once per test.
* Refactor tests to use a test builder
* Change all testQuery() methods to use the test builder.
Move test execution & verification into a test runner.
* SQL: Use timestamp_floor when granularity is not safe.
PR #12944 added a check at the execution layer to avoid materializing
excessive amounts of time-granular buckets. This patch modifies the SQL
planner to avoid generating queries that would throw such errors, by
switching certain plans to use the timestamp_floor function instead of
granularities. This applies both to the Timeseries query type, and the
GroupBy timestampResultFieldGranularity feature.
The patch also goes one step further: we switch to timestamp_floor
not just in the ETERNITY + non-ALL case, but also if the estimated
number of time-granular buckets exceeds 100,000.
Finally, the patch modifies the timestampResultFieldGranularity
field to consistently be a String rather than a Granularity. This
ensures that it can be round-trip serialized and deserialized, which is
useful when trying to execute the results of "EXPLAIN PLAN FOR" with
GroupBy queries that use the timestampResultFieldGranularity feature.
* Fix test, address PR comments.
* Fix ControllerImpl.
* Fix test.
* Fix unused import.
We introduce two new configuration keys that refine the query context security model controlled by druid.auth.authorizeQueryContextParams. When that value is set to true then two other configuration options become available:
druid.auth.unsecuredContextKeys: The set of query context keys that do not require a security check. Use this for the "white-list" of key to allow. All other keys go through the existing context key security checks.
druid.auth.securedContextKeys: The set of query context keys that do require a security check. Use this when you want to allow all but a specific set of keys: only these keys go through the existing context key security checks.
Both are set using JSON list format:
druid.auth.securedContextKeys=["secretKey1", "secretKey2"]
You generally set one or the other values. If both are set, unsecuredContextKeys acts as exceptions to securedContextKeys.
In addition, Druid defines two query context keys which always bypass checks because Druid uses them internally:
sqlQueryId
sqlStringifyArrays
* Expose HTTP Response headers from SqlResource
This change makes the SqlResource expose HTTP response
headers in the same way that the QueryResource exposes them.
Fundamentally, the change is to pipe the QueryResponse
object all the way through to the Resource so that it can
populate response headers. There is also some code
cleanup around DI, as there was a superfluous FactoryFactory
class muddying things up.
* more consistent expression error messages
* review stuff
* add NamedFunction for Function, ApplyFunction, and ExprMacro to share common stuff
* fixes
* add expression transform name to transformer failure, better parse_json error messaging
* SQL: Morph QueryMakerFactory into SqlEngine.
Groundwork for introducing an indexing-service-task-based SQL engine
under the umbrella of #12262. Also includes some other changes related
to improving error behavior.
Main changes:
1) Elevate the QueryMakerFactory interface (an extension point that allows
customization of how queries are made) into SqlEngine. SQL engines
can influence planner behavior through EngineFeatures, and can fully
control the mechanics of query execution using QueryMakers.
2) Remove the server-wide QueryMakerFactory choice, in favor of the choice
being made by the SQL entrypoint. The indexing-service-task-based
SQL engine would be associated with its own entrypoint, like
/druid/v2/sql/task.
Other changes:
1) Adjust DruidPlanner to try either DRUID or BINDABLE convention based
on analysis of the planned rels; never try both. In particular, we
no longer try BINDABLE when DRUID fails. This simplifies the logic
and improves error messages.
2) Adjust error message "Cannot build plan for query" to omit the SQL
query text. Useful because the text can be quite long, which makes it
easy to miss the text about the problem.
3) Add a feature to block context parameters used internally by the SQL
planner from being supplied by end users.
4) Add a feature to enable adding row signature to the context for
Scan queries. This is useful in building the task-based engine.
5) Add saffron.properties file that turns off sets and graphviz dumps
in "cannot plan" errors. Significantly reduces log spam on the Broker.
* Fixes from CI.
* Changes from review.
* Can vectorize, now that join-to-filter is on by default.
* Checkstyle! And variable renames!
* Remove throws from test.
* Refactor SqlLifecycle into statement classes
Create direct & prepared statements
Remove redundant exceptions from tests
Tidy up Calcite query tests
Make PlannerConfig more testable
* Build fixes
* Added builder to SqlQueryPlus
* Moved Calcites system properties to saffron.properties
* Build fix
* Resolve merge conflict
* Fix IntelliJ inspection issue
* Revisions from reviews
Backed out a revision to Calcite tests that didn't work out as planned
* Build fix
* Fixed spelling errors
* Fixed failed test
Prepare now enforces security; before it did not.
* Rebase and fix IntelliJ inspections issue
* Clean up exception handling
* Fix handling of JDBC auth errors
* Build fix
* More tweaks to security messages
* Introduce defaultOnDiskStorage config for groupBy
* add debug log to groupby query config
* Apply config change suggestion from review
* Remove accidental new lines
* update default value of new default disk storage config
* update debug log to have more descriptive text
* Make maxOnDiskStorage and defaultOnDiskStorage HumanRedadableBytes
* improve test coverage
* Provide default implementation to new default method on advice of reviewer
Refactors the DruidSchema and DruidTable abstractions to prepare for the Druid Catalog.
As we add the catalog, we’ll want to combine physical segment metadata information with “hints” provided by the catalog. This is best done if we tidy up the existing code to more clearly separate responsibilities.
This PR is purely a refactoring move: no functionality changed. There is no difference to user functionality or external APIs. Functionality changes will come later as we add the catalog itself.
DruidSchema
In the present code, DruidSchema does three tasks:
Holds the segment metadata cache
Interfaces with an external schema manager
Acts as a schema to Calcite
This PR splits those responsibilities.
DruidSchema holds the Calcite schema for the druid namespace, combining information fro the segment metadata cache, from the external schema manager and (later) from the catalog.
SegmentMetadataCache holds the segment metadata cache formerly in DruidSchema.
DruidTable
The present DruidTable class is a bit of a kitchen sink: it holds all the various kinds of tables which Druid supports, and uses if-statements to handle behavior that differs between types. Yet, any given DruidTable will handle only one such table type. To more clearly model the actual table types, we split DruidTable into several classes:
DruidTable becomes an abstract base class to hold Druid-specific methods.
DatasourceTable represents a datasource.
ExternalTable represents an external table, such as from EXTERN or (later) from the catalog.
InlineTable represents the internal case in which we attach data directly to a table.
LookupTable represents Druid’s lookup table mechanism.
The new subclasses are more focused: they can be selective about the data they hold and the various predicates since they represent just one table type. This will be important as the catalog information will differ depending on table type and the new structure makes adding that logic cleaner.
DatasourceMetadata
Previously, the DruidSchema segment cache would work with DruidTable objects. With the catalog, we need a layer between the segment metadata and the table as presented to Calcite. To fix this, the new SegmentMetadataCache class uses a new DatasourceMetadata class as its cache entry to hold only the “physical” segment metadata information: it is up to the DruidTable to combine this with the catalog information in a later PR.
More Efficient Table Resolution
Calcite provides a convenient base class for schema objects: AbstractSchema. However, this class is a bit too convenient: all we have to do is provide a map of tables and Calcite does the rest. This means that, to resolve any single datasource, say, foo, we need to cache segment metadata, external schema information, and catalog information for all tables. Just so Calcite can do a map lookup.
There is nothing special about AbstractSchema. We can handle table lookups ourselves. The new AbstractTableSchema does this. In fact, all the rest of Calcite wants is to resolve individual tables by name, and, for commands we don’t use, to provide a list of table names.
DruidSchema now extends AbstractTableSchema. SegmentMetadataCache resolves individual tables (and provides table names.)
DruidSchemaManager
DruidSchemaManager provides a way to specify table schemas externally. In this sense, it is similar to the catalog, but only for datasources. It originally followed the AbstractSchema pattern: it implements provide a map of tables. This PR provides new optional methods for the table lookup and table names operations. The default implementations work the same way that AbstractSchema works: we get the entire map and pick out the information we need. Extensions that use this API should be revised to support the individual operations instead. Druid code no longer calls the original getTables() method.
The PR has one breaking change: since the DruidSchemaManager map is read-only to the rest of Druid, we should return a Map, not a ConcurrentMap.
add NumericRangeIndex interface and BoundFilter support
changes:
* NumericRangeIndex interface, like LexicographicalRangeIndex but for numbers
* BoundFilter now uses NumericRangeIndex if comparator is numeric and there is no extractionFn
* NestedFieldLiteralColumnIndexSupplier.java now supports supplying NumericRangeIndex for single typed numeric nested literal columns
* better faster stronger and (ever so slightly) more understandable
* more tests, fix bug
* fix style
* Preserve column order in DruidSchema, SegmentMetadataQuery.
Instead of putting columns in alphabetical order. This is helpful
because it makes query order better match ingestion order. It also
allows tools, like the reindexing flow in the web console, to more
easily do follow-on ingestions using a column order that matches the
pre-existing column order.
We prefer the order from the latest segments. The logic takes all
columns from the latest segments in the order they appear, then adds
on columns from older segments after those.
* Additional test adjustments.
* Adjust imports.
* Frame format for data transfer and short-term storage.
As we move towards query execution plans that involve more transfer
of data between servers, it's important to have a data format that
provides for doing this more efficiently than the options available to
us today.
This patch adds:
- Columnar frames, which support fast querying.
- Row-based frames, which support fast sorting via memory comparison
and fast whole-row copies via memory copying.
- Frame files, a container format that can be stored on disk or
transferred between servers.
The idea is we should use row-based frames when data is expected to
be sorted, and columnar frames when data is expected to be queried.
The code in this patch is not used in production yet. Therefore, the
patch involves minimal changes outside of the org.apache.druid.frame
package. The main ones are adjustments to SqlBenchmark to add benchmarks
for queries on frames, and the addition of a "forEach" method to Sequence.
* Fixes based on tests, static analysis.
* Additional fixes.
* Skip DS mapping tests on JDK 14+
* Better JDK checking in tests.
* Fix imports.
* Additional comment.
* Adjustments from code review.
* Update test case.
* Poison StupidPool and fix resource leaks
There are various resource leaks from test setup as well as some
corners in query processing. We poison the StupidPool to start failing
tests when the leaks come and fix any issues uncovered from that so
that we can start from a clean baseline.
Unfortunately, because of how poisoning works,
we can only fail future checkouts from the same pool,
which means that there is a natural race between a
leak happening -> GC occurs -> leak detected -> pool poisoned.
This race means that, depending on interleaving of tests,
if the very last time that an object is checked out
from the pool leaks, then it won't get caught.
At some point in the future, something will catch it,
however and from that point on it will be deterministic.
* Remove various things left over from iterations
* Clean up FilterAnalysis and add javadoc on StupidPool
* Revert changes to .idea/misc.xml that accidentally got pushed
* Style and test branches
* Stylistic woes
Often users are submitting queries, and ingestion specs that work only if the relevant extension is not loaded. However, the error is too technical for the users and doesn't suggest them to check for missing extensions. This PR modifies the error message so users can at least check their settings before assuming that the error is because of a bug.
* Adding zstandard compression library
* 1. Took @clintropolis's advice to have ZStandard decompressor use the byte array when the buffers are not direct.
2. Cleaned up checkstyle issues.
* Fixing zstandard version to latest stable version in pom's and updating license files
* Removing zstd from benchmarks and adding to processing (poms)
* fix the intellij inspection issue
* Removing the prefix v for the version in the license check for ztsd
* Fixing license checks
Co-authored-by: Rahul Gidwani <r_gidwani@apple.com>
* Direct UTF-8 access for "in" filters.
Directly related:
1) InDimFilter: Store stored Strings (in ValuesSet) plus sorted UTF-8
ByteBuffers (in valuesUtf8). Use valuesUtf8 whenever possible. If
necessary, the input set is copied into a ValuesSet. Much logic is
simplified, because we always know what type the values set will be.
I think that there won't even be an efficiency loss in most cases.
InDimFilter is most frequently created by deserialization, and this
patch updates the JsonCreator constructor to deserialize
directly into a ValuesSet.
2) Add Utf8ValueSetIndex, which InDimFilter uses to avoid UTF-8 decodes
during index lookups.
3) Add unsigned comparator to ByteBufferUtils and use it in
GenericIndexed.BYTE_BUFFER_STRATEGY. This is important because UTF-8
bytes can be compared as bytes if, and only if, the comparison
is unsigned.
4) Add specialization to GenericIndexed.singleThreaded().indexOf that
avoids needless ByteBuffer allocations.
5) Clarify that objects returned by ColumnIndexSupplier.as are not
thread-safe. DictionaryEncodedStringIndexSupplier now calls
singleThreaded() on all relevant GenericIndexed objects, saving
a ByteBuffer allocation per access.
Also:
1) Fix performance regression in LikeFilter: since #12315, it applied
the suffix matcher to all values in range even for type MATCH_ALL.
2) Add ObjectStrategy.canCompare() method. This fixes LikeFilterBenchmark,
which was broken due to calls to strategy.compare in
GenericIndexed.fromIterable.
* Add like-filter implementation tests.
* Add in-filter implementation tests.
* Add tests, fix issues.
* Fix style.
* Adjustments from review.
* Add ipaddress library as dependency.
* IPv4 functions to use the inet.ipaddr package.
* Remove unused imports.
* Add new function.
* Minor rename.
* Add more unit tests.
* IPv4 address expr utils unit tests and address options.
* Adjust the IPv4Util functions.
* Move the UTs a bit around.
* Javadoc comments.
* Add license info for IPAddress.
* Fix groupId, artifact and version in license.yaml.
* Remove redundant subnet in messages - fixes UT.
* Remove unused commons-net dependency for /processing project.
* Make class and methods public so it can be accessed.
* Add initial version of benchmark
* Add subnetutils package for benchmarks.
* Auto generate ip addresses.
* Add more v4 address representations in setup to avoid bias.
* Use ThreadLocalRandom to avoid forbidden API usage.
* Adjust IPv4AddressBenchmark to adhere to codestyle rules.
* Update ipaddress library to latest 5.3.4
* Add ipaddress package dependency to benchmarks project.
Following up on #12315, which pushed most of the logic of building ImmutableBitmap into BitmapIndex in order to hide the details of how column indexes are implemented from the Filter implementations, this PR totally refashions how Filter consume indexes. The end result, while a rather dramatic reshuffling of the existing code, should be extraordinarily flexible, eventually allowing us to model any type of index we can imagine, and providing the machinery to build the filters that use them, while also allowing for other column implementations to implement the built-in index types to provide adapters to make use indexing in the current set filters that Druid provides.
* DimensionRangeShardSpec speed boost.
Calling isEmpty() and equals() on RangeSets is expensive, because these
fall back on default implementations that call size(). And size() is
_also_ a default implementation that iterates the entire collection.
* Fix and test from code review.
* JvmMonitor: Handle more generation and collector scenarios.
ZGC on Java 11 only has a generation 1 (there is no 0). This causes
a NullPointerException when trying to extract the spacesCount for
generation 0. In addition, ZGC on Java 15 has a collector number 2
but no spaces in generation 2, which breaks the assumption that
collectors always have same-numbered spaces.
This patch adjusts things to be more robust, enabling the JvmMonitor
to work properly for ZGC on both Java 11 and 15.
* Test adjustments.
* Improve surefire arglines.
* Need a placeholder
* Vectorizing Latest aggregator Part 1
* Updating benchmark tests
* Changing appropriate logic for vectors for null handling
* Introducing an abstract class and moving the commonalities there
* Adding vectorization for StringLast aggregator (initial version)
* Updated bufferized version of numeric aggregators
* Adding some javadocs
* Making sure this PR vectorizes numeric latest agg only
* Adding another benchmarking test
* Fixing intellij inspections
* Adding tests for double
* Adding test cases for long and float
* Updating testcases
* Checkstyle oops..
* One tiny change in test case
* Fixing spotbug and rhs not being used
Currently, the CNF conversion of a filter is unbounded, which means that it can create as many filters as possible thereby also leading to OOMs in historical heap. We should throw an error or disable CNF conversion if the filter count starts getting out of hand. There are ways to do CNF conversion with linear increase in filters as well but that has been left out of the scope of this change since those algorithms add new variables in the predicate - which can be contentious.
* perf: indexing: Introduce a bulk getValuesInto function to read values in bulk
If large number of values are required from DimensionDictionary
during indexing, fetch them all in a single lock/unlock instead of
lock/unlock each individual item.
* refactor: rename key to keys in function args
* fix: check explicitly that argument length on arrays match
* refactor: getValuesInto renamed to getValues, now creates and returns a new T[] rather than filling
Fixes#12022
### Description
The current implementations of memory estimation in `OnHeapIncrementalIndex` and `StringDimensionIndexer` tend to over-estimate which leads to more persistence cycles than necessary.
This PR replaces the max estimation mechanism with getting the incremental memory used by the aggregator or indexer at each invocation of `aggregate` or `encode` respectively.
### Changes
- Add new flag `useMaxMemoryEstimates` in the task context. This overrides the same flag in DefaultTaskConfig i.e. `druid.indexer.task.default.context` map
- Add method `AggregatorFactory.factorizeWithSize()` that returns an `AggregatorAndSize` which contains
the aggregator instance and the estimated initial size of the aggregator
- Add method `Aggregator.aggregateWithSize()` which returns the incremental memory used by this aggregation step
- Update the method `DimensionIndexer.processRowValsToKeyComponent()` to return the encoded key component as well as its effective size in bytes
- Update `OnHeapIncrementalIndex` to use the new estimations only if `useMaxMemoryEstimates = false`
DruidSchema consists of a concurrent HashMap of DataSource -> Segement -> AvailableSegmentMetadata. AvailableSegmentMetadata contains RowSignature of the segment, and for each segment, a new object is getting created. RowSignature is an immutable class, and hence it can be interned, and this can lead to huge savings of memory being used in broker, since a lot of the segments of a table would potentially have same RowSignature.
* clean up the balancing code around the batched vs deprecated way of sampling segments to balance
* fix docs, clarify comments, add deprecated annotations to legacy code
* remove unused variable
* update dynamic config dialog in console to state percentOfSegmentsToConsiderPerMove deprecated
* fix dynamic config text for percentOfSegmentsToConsiderPerMove
* run prettier to cleanup coordinator-dynamic-config.tsx changes
* update jest snapshot
* update documentation per review feedback
changes:
* adds new config, druid.expressions.useStrictBooleans which make longs the official boolean type of all expressions
* vectorize logical operators and boolean functions, some only if useStrictBooleans is true
* Code cleanup from query profile project
* Fix spelling errors
* Fix Javadoc formatting
* Abstract out repeated test code
* Reuse constants in place of some string literals
* Fix up some parameterized types
* Reduce warnings reported by Eclipse
* Reverted change due to lack of tests
Kashif Faraz
Gian Merlino
Jason Koch
somu-imply
Clint Wylie
Paul Rogers
Rohan Garg
imply-cheddar
Abhishek Agarwal
Lucas Capistrant
Dr. Sizzles
Abhishek Radhakrishnan
Nishant Bangarwa
Gian Merlino
dependabot[bot]
Jihoon Son
Maytas Monsereenusorn
Jonathan Wei
Laksh Singla