fix: honor required fields in jackson @JsonProperty annotations

Author: elagerho

modules/openapi-generator/src/main/resources/Java/jackson_annotations.mustache

@@ -4,7 +4,7 @@
  * If the field is required, always include it, even if it is null.
  * Else use custom behaviour, IOW use whatever is defined on the object mapper
  }}
-  @JsonProperty(JSON_PROPERTY_{{nameInSnakeCase}})
+  @JsonProperty(value = JSON_PROPERTY_{{nameInSnakeCase}}, required = {{required}})
   @JsonInclude({{#isMap}}{{#items.isNullable}}content = JsonInclude.Include.ALWAYS, {{/items.isNullable}}{{/isMap}}value = JsonInclude.Include.{{#required}}ALWAYS{{/required}}{{^required}}USE_DEFAULTS{{/required}})
 {{#withXml}}
   @JacksonXmlProperty(localName = "{{items.xmlName}}{{^items.xmlName}}{{xmlName}}{{^xmlName}}{{baseName}}{{/xmlName}}{{/items.xmlName}}"{{#isXmlAttribute}}, isAttribute = true{{/isXmlAttribute}}{{#xmlNamespace}}, namespace = "{{.}}"{{/xmlNamespace}})

modules/openapi-generator/src/main/resources/Java/pojo.mustache

@@ -108,7 +108,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
   {{#jsonb}}@JsonbCreator{{/jsonb}}{{#jackson}}@JsonCreator{{/jackson}}
   public {{classname}}(
   {{#readOnlyVars}}
-    {{#jsonb}}@JsonbProperty(value = "{{baseName}}"{{^required}}, nullable = true{{/required}}){{/jsonb}}{{#jackson}}@JsonProperty(JSON_PROPERTY_{{nameInSnakeCase}}){{/jackson}} {{{datatypeWithEnum}}} {{name}}{{^-last}}, {{/-last}}
+    {{#jsonb}}@JsonbProperty(value = "{{baseName}}"{{^required}}, nullable = true{{/required}}){{/jsonb}}{{#jackson}}@JsonProperty(value = JSON_PROPERTY_{{nameInSnakeCase}}, required = {{required}}){{/jackson}} {{{datatypeWithEnum}}} {{name}}{{^-last}}, {{/-last}}
   {{/readOnlyVars}}
   ) {
     this();
@@ -123,7 +123,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
   /**
    * Constructor with all args parameters
    */
-  public {{classname}}({{#vendorExtensions.x-java-all-args-constructor-vars}}{{#jsonb}}@JsonbProperty(value = "{{baseName}}"{{^required}}, nullable = true{{/required}}){{/jsonb}}{{#jackson}}@JsonProperty(JSON_PROPERTY_{{nameInSnakeCase}}){{/jackson}} {{{datatypeWithEnum}}} {{name}}{{^-last}}, {{/-last}}{{/vendorExtensions.x-java-all-args-constructor-vars}}) {
+  public {{classname}}({{#vendorExtensions.x-java-all-args-constructor-vars}}{{#jsonb}}@JsonbProperty(value = "{{baseName}}"{{^required}}, nullable = true{{/required}}){{/jsonb}}{{#jackson}}@JsonProperty(value = JSON_PROPERTY_{{nameInSnakeCase}}, required = {{required}}){{/jackson}} {{{datatypeWithEnum}}} {{name}}{{^-last}}, {{/-last}}{{/vendorExtensions.x-java-all-args-constructor-vars}}) {
 {{#parent}}
     super({{#parentVars}}{{name}}{{^-last}}, {{/-last}}{{/parentVars}});
 {{/parent}}
@@ -252,7 +252,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
     return {{name}};
   }
   {{/vendorExtensions.x-is-jackson-optional-nullable}}{{#vendorExtensions.x-is-jackson-optional-nullable}}
-  @JsonProperty(JSON_PROPERTY_{{nameInSnakeCase}})
+  @JsonProperty(value = JSON_PROPERTY_{{nameInSnakeCase}}, required = {{required}})
   {{#isReadOnly}}private{{/isReadOnly}}{{^isReadOnly}}public{{/isReadOnly}} void {{setter}}_JsonNullable(JsonNullable<{{{datatypeWithEnum}}}> {{name}}) {
     {{! For getters/setters that have name differing from attribute name, we must include setter (albeit private) for jackson to be able to set the attribute}}
     this.{{name}} = {{name}};