GitHub user nickwallen opened a pull request:
https://github.com/apache/incubator-metron/pull/301
METRON-490 Stellar Validation of Required Parameters
### [METRON-490](https://issues.apache.org/jira/browse/METRON-490)
Currently, each Stellar function handles validation of required function
parameters in its own way. In some cases, we have functions that throw an
IndexOutOfBoundsException, in other cases the function will produce its own
error message and exception.
There needs to be a standard mechanism to validate required function
parameters. This mechanism should handle missing parameters gracefully and
provide an error message that makes sense to a user. The handling should be
accessible across all functions.
### Changes
* Added an additional Stellar annotation called `requiredParams`.
* Added a method to `BaseStellarFunction.validate` to validate the
`requiredParams`.
* Use of the annotation field and validation mechanism is optional.
* Modified the Stellar STATS_* functions to use this functionality.
* If an incorrect type is specified, an IllegalArgumentException is thrown
with a message like
```
SOME_FUNCTION: unexpected parameter [2]: expected class
java.lang.Integer, actual class java.lang.String`
```
* If a required parameter is missing, an IllegalArgumentException is thrown
with a message like:
```
SOME_FUNCTION: parameter missing [2]: expected class java.lang.Integer
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/nickwallen/incubator-metron METRON-490
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-metron/pull/301.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #301
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