A few parts of the Checker Framework have more permissive licenses.

 * The annotations are licensed under the MIT License.  (The text of this
   license appears below.)  More specifically, all the parts of the Checker
   Framework that you might want to include with your own program use the
   MIT License.  This is the checker-qual.jar file and all the files that
   appear in it:  every file in a qual/ directory, plus utility files such
   as NullnessUtil.java, RegexUtil.java, SignednessUtil.java, etc.
   In addition, the cleanroom implementations of third-party annotations,
   which the Checker Framework recognizes as aliases for its own
   annotations, are licensed under the MIT License.

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MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

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