Add feature in JsonBodyFilters to replace value by custom function.

[dnandola-wyze]

Summary:
Currently Json Body filters obfusicate the property values with a replacement string. eg. "XXX". However, users may want to do a custom obfusication of these values for eg. Hash of the given value. In order to make it extensible, add a function in JSonBodyFilter to convert a primitive JSON using a custom function provided by the user.

Description:
The following changes are made:

• Make PrimitiveJsonPropertyBodyFilter as abstract class, where child class will provide replacement function.
• Change Pattern regular expression to add groupname "propertyValue" for grouping the value.
• Add two subclass for string replacement and function replacement.

Motivation and Context

Adds extension to help users create a custom filter function.
Fixes #851
#755

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation. (Not sure about this)
• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[whiskeysierra]

I'd prefer an easier change:

• Leave the structure of PrimitiveJsonPropertyBodyFilter as it is
• Change private final String replacement to private final BinaryOperator<String> replacement
• Change all static methods that are calling new PrimitiveJsonPropertyBodyFilter(..., replacement) to new PrimitiveJsonPropertyBodyFilter(..., (name, value) -> replacement)

[whiskeysierra]

In other words, make the current default implementation (string replacement) a special case of the new default implementation (function-based replacement).

[dnandola-wyze]

In other words, make the current default implementation (string replacement) a special case of the new default implementation (function-based replacement).

I actually had implemented it that way initially. The issue with that is it will break the BodyFilter merge functionality. Because it will become a bit complicated to compare replacement function instead of replacement string:

public boolean compatibleWith(final PrimitiveJsonPropertyBodyFilter that) {
return pattern.equals(that.pattern)
&& replacement.equals(that.replacement);
}

[whiskeysierra]

That works if you have a non-anonymous function. So instead of my suggestion from above ((name, value) -> replacement) you need a real class that overrides equals/hashCode and then it works:

@AllArgsConstructor
private static final class StaticReplacement implements BinaryOperator<String> {

    private final String replacement;

    // TODO apply
    // TODO equals/hashCode
}

[dnandola-wyze]

Thanks for the feedback. I hadn't thought of that. I have updated the PR with the changes.

[whiskeysierra]

Interesting. I didn't realize that we always quoted here. Means there is no way to replace booleans and numbers because they will become strings.

[whiskeysierra]

Looks good. Let me fix the issue in the master first. Might take a couple of days.

[whiskeysierra]

There is no need for this class to be generic, is there?

[dnandola-wyze]

Yeah. Not in current use cases, I guess. It can be removed if you want.

[whiskeysierra]

Same here. T is always String, no need to be generic.

[dnandola-wyze]

Not in this case. It could be number or boolean. Or I guess, it can be passed as string through constructor.

[whiskeysierra]

If you rebase onto main, then I can fix the final review comments myself before releasing.

[dnandola-wyze]

I rebased it with main.

[whiskeysierra]

👍