fix(core): serialize default inputs

core/src/main/java/io/kestra/core/models/flows/Input.java

@@ -1,6 +1,5 @@
 package io.kestra.core.models.flows;
 
-import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonSetter;
 import com.fasterxml.jackson.annotation.JsonSubTypes;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
@@ -39,7 +38,6 @@
     @JsonSubTypes.Type(value = URIInput.class, name = "URI"),
     @JsonSubTypes.Type(value = MultiselectInput.class, name = "MULTISELECT")
 })
-@JsonInclude(JsonInclude.Include.NON_DEFAULT)
 public abstract class Input<T> implements Data {
     @NotNull
     @NotBlank

core/src/test/java/io/kestra/core/serializers/YamlFlowParserTest.java

@@ -123,10 +123,10 @@ void inputsFailed() {
     void inputs() {
         Flow flow = this.parse("flows/valids/inputs.yaml");
 
-        assertThat(flow.getInputs().size(), is(27));
-        assertThat(flow.getInputs().stream().filter(Input::getRequired).count(), is(9L));
+        assertThat(flow.getInputs().size(), is(28));
+        assertThat(flow.getInputs().stream().filter(Input::getRequired).count(), is(10L));
         assertThat(flow.getInputs().stream().filter(r -> !r.getRequired()).count(), is(18L));
-        assertThat(flow.getInputs().stream().filter(r -> r.getDefaults() != null).count(), is(1L));
+        assertThat(flow.getInputs().stream().filter(r -> r.getDefaults() != null).count(), is(2L));
         assertThat(flow.getInputs().stream().filter(r -> r instanceof StringInput && ((StringInput)r).getValidator() != null).count(), is(1L));
     }
 

core/src/test/resources/flows/valids/inputs.yaml

@@ -95,6 +95,11 @@ inputs:
 - name: array
   type: ARRAY
   itemType: INT
+# required true and an empty default value will only work if we correctly serialize default values which is what this input is about to test.
+- name: empty
+  type: STRING
+  defaults: ''
+  required: true
 
 tasks:
 - id: string