Allow sets to have an empty default value

[bitfrost]

No description provided.

[joelittlejohn]

Hi @bitfrost, thanks for submitting this, could you help me understand why this PR is needed? An empty set will be created already if you omit the "default" rule, and (as far as I can tell) you'll already get a default empty set if your schema has default: [].

Are you combining this with initializeCollections=false?

One other small thing: if this change is needed then we should apply it to both getDefaultSet and getDefaultList.

[bitfrost]

Hi @joelittlejohn, I am sorry I did not see your reply until this morning,
I want to specify an empty array explicitly for javascript usage of the schema, but the following valid schema results in a compile error for the generated java code.

This change as far as I can tell was already been applied to getDefaultList to close similar issue.
I am not using initializeCollections=false. getDefaultList/getDefaultSet are very similar, i considered collapsing them to one function instead of making this 1 line change, but got lazy :)

Example:

"widgets" : {
      "description" : "An array of widgets.",
      "type" : "array",
      "minItems" : 0,
      "items" : {
          "$ref" : "widget.json"
      },
      "default" : [],
      "uniqueItems" : true
    }

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project dashboard-service: Compilation failure
[ERROR] /Users/kobrien/dev/dashboard-service/target/generated-sources/com/cvent/board/core/Dashboard.java:[158,35] no suitable constructor found for LinkedHashSet(java.util.List<java.lang.Object>)
[ERROR] constructor java.util.LinkedHashSet.LinkedHashSet(java.util.Collection<? extends com.cvent.board.core.Widget>) is not applicable
[ERROR] (actual argument java.util.List<java.lang.Object> cannot be converted to java.util.Collection<? extends com.cvent.board.core.Widget> by method invocation conversion)
[ERROR] constructor java.util.LinkedHashSet.LinkedHashSet() is not applicable
[ERROR] (actual and formal argument lists differ in length)
[ERROR] constructor java.util.LinkedHashSet.LinkedHashSet(int) is not applicable
[ERROR] (actual argument java.util.List<java.lang.Object> cannot be converted to int by method invocation conversion)
[ERROR] constructor java.util.LinkedHashSet.LinkedHashSet(int,float) is not applicable
[ERROR] (actual and formal argument lists differ in length)

Offending generated code:

  private Set<Widget> widgets = new LinkedHashSet<Widget>(Arrays.asList());

[joelittlejohn]

Thanks for your reply, I see exactly what you mean now.