Github user markap14 commented on the issue:
https://github.com/apache/nifi/pull/2205
@pvillard31 one note to consider is that a Processor is able to also
provide its own set of 'variables' to the EL when evaluated. For example, when
RouteText is used with a "Matching Strategy" of "Satisfies Expression", the
variables "line" and "lineNo" are also available in EL to make routing
decisions. I think it would be nice for this to be better reflected here as
well, such as :
```
.expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
.expressionLanguageVariable("line", "The line of text to evaluate")
.expressionLanguageVariable("lineNo", "The 1-based number that represents
which line in the incoming FlowFile this line is")
```
Additionally, the Mock Framework currently will throw an Exception if a
Property indicates that EL is supported but does not evaluate the Expression
Language (or vice versa). It probably makes sense to update that to also ensure
that the proper scope was used (if VARIABLE_REGISTRY is specified but FlowFile
attributes are evaluated, that should fail). This could potentially be done as
a separate JIRA, though.
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