Make global parameters singletons

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Description

Currently, global parameters are being rebuilt inside each plugin which has resulted in discrepancies where the global parameter is not configured the same way within a plugin.

Steps to Reproduce

1. [First Step]
2. [Second Step]
3. [and so on…]

Expected behaviour: global parameters built outside of plugin

Actual behaviour: global parameters built inside each plugin Reproduces how often: 100%

Additional Information

Any additional information, configuration or data that might be necessary to reproduce the issue.

[arcturus2]

Just jumping in here too. For some more background had a look at the following and see how DateTimeRangeParameterType is being built again.

https://github.com/constellation-app/constellation-training/blob/32d97260c4e7b1bfeebe3ed30435fd215ce8b2a5/constellation-training-solutions/TrainingSolutions/src/au/gov/asd/tac/constellation/training/solutions/chapter4/ChainCitiesPlugin.java#L60

To be able to use the date range the user wants to query on the DateTimeRangeParameterType needs to be available to the plugin. you can see how its being used

https://github.com/constellation-app/constellation-training/blob/32d97260c4e7b1bfeebe3ed30435fd215ce8b2a5/constellation-training-solutions/TrainingSolutions/src/au/gov/asd/tac/constellation/training/solutions/chapter4/ChainCitiesPlugin.java#L68

So back on line 60 what we should do rather than newing instances is get the existing instance of DateTimeRangeParameterType - i.e these should be singletons.

I was thinking of using a builder pattern so when say build - it will either built it or give you an instance of it if the builder has previously built it.

Happy for other suggestions to. Note that global parameters are used in other modules (like the Training module suite) so minimal breaking API changes is highly desirable.

[sol695510]

From memory, the crux of the issue was that the current global parameters implementation relies on each plugin developer re-building those parameters using a common parameter id. What we really want is for global parameters to already have been built and for all plugins to have access to them.

I’d imagine this being analogous to how any plugin can access a pre-built version of any SchemaVertexType via its SchemaConcept class. So you might have some generic functions in the GlobalParameters class for things like “lookup by string” if it makes sense, but the standard way of accessing these parameters would be something like:

parameters.addParameter(CoreGlobalParameters.QUERY_NAME_PARAMETER)
parameters.addParameter(CoreGlobalParameters.DATETIME_RANGE_PARAMETER)

I think the implementation here #559 is similar to what you’ve described. Advise if otherwise.