chore: Avoid the use of JsonInclude.Include.NON_DEFAULT where possible

For Kotlin, the meaning of this annotation is misleading, as it does not
refer to the value explicitly assigned to a property by default, but to
the value used if the underlying Java field was uninitialized. I.e., for
`boolean` that would be always `false`, and for `int` it would be always
`0`, see [1].

To avoid this confusion, do not use that annotation value where it can
be replaced with `JsonInclude.Include.NON_EMPTY`, which also omits Java
field implicit default values [2], like `null` for nullable types.

[1]: FasterXML/jackson-module-kotlin#478
[2]: https://www.javadoc.io/doc/com.fasterxml.jackson.core/jackson-annotations/2.19.2/com/fasterxml/jackson/annotation/JsonInclude.Include.html#NON_EMPTY

Signed-off-by: Sebastian Schuberth <[email protected]>

Author: sschuberth

model/src/main/kotlin/Defect.kt

@@ -30,7 +30,7 @@ import java.time.Instant
  * Instances of this class are created by advisor implementations that retrieve information about known defects in
  * packages.
  */
-@JsonInclude(JsonInclude.Include.NON_DEFAULT)
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
 data class Defect(
     /**
      * The (external) ID of this defect. This is a string used by a concrete issue tracker system to reference this

model/src/main/kotlin/DependencyGraph.kt

@@ -72,7 +72,7 @@ typealias NodeDependencies = Map<DependencyGraphNode, List<DependencyGraphNode>>
  * Then, by following the *edges* starting from these *nodes*, the set of transitive dependencies can be determined.
  * The numeric indices can be resolved via the *packages* list.
  */
-@JsonInclude(JsonInclude.Include.NON_DEFAULT)
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
 data class DependencyGraph(
     /**
      * A list with the identifiers of the packages that appear in the dependency graph. This list is used to resolve

model/src/main/kotlin/Package.kt

@@ -61,7 +61,7 @@ data class Package(
     /**
      * The set of authors declared for this package.
      */
-    @JsonInclude(JsonInclude.Include.NON_DEFAULT)
+    @JsonInclude(JsonInclude.Include.NON_EMPTY)
     @JsonSerialize(converter = StringSortedSetConverter::class)
     val authors: Set<String> = emptySet(),
 

model/src/main/kotlin/PackageReference.kt

@@ -32,8 +32,7 @@ import org.ossreviewtoolkit.model.utils.PackageReferenceSortedSetConverter
  * A human-readable reference to a software [Package]. Each package reference itself refers to other package
  * references that are dependencies of the package.
  */
-// Do not serialize default values to reduce the size of the result file.
-@JsonInclude(JsonInclude.Include.NON_DEFAULT)
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
 data class PackageReference(
     /**
      * The identifier of the package.

model/src/main/kotlin/Project.kt

@@ -58,7 +58,7 @@ data class Project(
     /**
      * The set of authors declared for this project.
      */
-    @JsonInclude(JsonInclude.Include.NON_DEFAULT)
+    @JsonInclude(JsonInclude.Include.NON_EMPTY)
     @JsonSerialize(converter = StringSortedSetConverter::class)
     val authors: Set<String> = emptySet(),