diff --git a/src/generators/java/presets/JacksonPreset.ts b/src/generators/java/presets/JacksonPreset.ts
index ce48744183..c0a95ed026 100644
--- a/src/generators/java/presets/JacksonPreset.ts
+++ b/src/generators/java/presets/JacksonPreset.ts
@@ -103,11 +103,16 @@ ${content}`;
               union instanceof ConstrainedReferenceModel &&
               union.ref instanceof ConstrainedObjectModel
             ) {
-              const discriminatorProp =
-                union.ref.properties[discriminator.discriminator].property;
-
-              if (discriminatorProp.options.const) {
-                return `  @JsonSubTypes.Type(value = ${union.name}.class, name = "${discriminatorProp.options.const.originalInput}")`;
+              const discriminatorProp = Object.values(
+                union.ref.properties
+              ).find(
+                (model) =>
+                  model.unconstrainedPropertyName ===
+                  discriminator.discriminator
+              );
+
+              if (discriminatorProp?.property.options.const) {
+                return `  @JsonSubTypes.Type(value = ${union.name}.class, name = "${discriminatorProp.property.options.const.originalInput}")`;
               }
             }
 
diff --git a/src/helpers/ConstrainHelpers.ts b/src/helpers/ConstrainHelpers.ts
index be84756be6..72409b793a 100644
--- a/src/helpers/ConstrainHelpers.ts
+++ b/src/helpers/ConstrainHelpers.ts
@@ -329,8 +329,11 @@ function addDiscriminatorTypeToUnionModel(
       const ref = union.ref;
 
       if (ref instanceof ConstrainedObjectModel) {
-        const discriminatorProp =
-          ref.properties[constrainedModel.options.discriminator.discriminator];
+        const discriminatorProp = Object.values(ref.properties).find(
+          (model) =>
+            model.unconstrainedPropertyName ===
+            constrainedModel.options.discriminator?.discriminator
+        );
 
         if (discriminatorProp) {
           propertyTypes.add(discriminatorProp.property.type);
diff --git a/test/generators/java/presets/JacksonPreset.spec.ts b/test/generators/java/presets/JacksonPreset.spec.ts
index e140589a82..7cf5bb25c9 100644
--- a/test/generators/java/presets/JacksonPreset.spec.ts
+++ b/test/generators/java/presets/JacksonPreset.spec.ts
@@ -1,4 +1,3 @@
-import { AsyncapiV2Schema } from '../../../../src';
 import { JavaGenerator, JAVA_JACKSON_PRESET } from '../../../../src/generators';
 
 describe('JAVA_JACKSON_PRESET', () => {
@@ -59,7 +58,7 @@ describe('JAVA_JACKSON_PRESET', () => {
             Vehicle: {
               payload: {
                 title: 'Vehicle',
-                discriminator: 'vehicleType',
+                discriminator: 'vehicle_type',
                 oneOf: [
                   { $ref: '#/components/schemas/Car' },
                   { $ref: '#/components/schemas/Truck' }
@@ -72,7 +71,7 @@ describe('JAVA_JACKSON_PRESET', () => {
               title: 'Car',
               type: 'object',
               properties: {
-                vehicleType: { type: 'string' },
+                vehicle_type: { type: 'string' },
                 name: { type: 'string' }
               }
             },
@@ -80,7 +79,7 @@ describe('JAVA_JACKSON_PRESET', () => {
               title: 'Truck',
               type: 'object',
               properties: {
-                vehicleType: { type: 'string' },
+                vehicle_type: { type: 'string' },
                 name: { type: 'string' }
               }
             }
diff --git a/test/generators/java/presets/__snapshots__/JacksonPreset.spec.ts.snap b/test/generators/java/presets/__snapshots__/JacksonPreset.spec.ts.snap
index c4cc7a48e3..f7d1757aab 100644
--- a/test/generators/java/presets/__snapshots__/JacksonPreset.spec.ts.snap
+++ b/test/generators/java/presets/__snapshots__/JacksonPreset.spec.ts.snap
@@ -55,7 +55,7 @@ exports[`JAVA_JACKSON_PRESET should render Jackson annotations for enum 1`] = `
 
 exports[`JAVA_JACKSON_PRESET union handle oneOf with AsyncAPI discriminator with Jackson 1`] = `
 Array [
-  "@JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.EXISTING_PROPERTY, property=\\"vehicleType\\", visible=true)
+  "@JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.EXISTING_PROPERTY, property=\\"vehicle_type\\", visible=true)
 @JsonSubTypes({
   @JsonSubTypes.Type(value = Car.class, name = \\"Car\\"),
   @JsonSubTypes.Type(value = Truck.class, name = \\"Truck\\")
@@ -67,7 +67,7 @@ public interface Vehicle {
   String getVehicleType();
 }",
   "public class Car implements Vehicle {
-  @JsonProperty(\\"vehicleType\\")
+  @JsonProperty(\\"vehicle_type\\")
   @JsonInclude(JsonInclude.Include.NON_NULL)
   private String vehicleType;
   @JsonProperty(\\"name\\")
@@ -86,7 +86,7 @@ public interface Vehicle {
   public void setAdditionalProperties(Map<String, Object> additionalProperties) { this.additionalProperties = additionalProperties; }
 }",
   "public class Truck implements Vehicle {
-  @JsonProperty(\\"vehicleType\\")
+  @JsonProperty(\\"vehicle_type\\")
   @JsonInclude(JsonInclude.Include.NON_NULL)
   private String vehicleType;
   @JsonProperty(\\"name\\")