This adds a gradle task called generateContextDoc in the Painless module. The
task will start a cluster, issue commands against the context rest api for
Painless, and generate documentation for each API per context. Each context
has a first page of classes sorted by package first and class name second,
along with a page per package with each classes' constructors, methods, and
fields. A link is generated for each constructor, method, and field to a JavaDoc
page when possible.
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