Fix a bug where a Staged interface for a required property generates …

…a setter with the wrong type parameter.

build.gradle

@@ -87,6 +87,7 @@ repositories {
 if (JavaVersion.current() <= JavaVersion.VERSION_11) {
     sourceCompatibility = JavaVersion.VERSION_1_6
     targetCompatibility = JavaVersion.VERSION_1_6
+    sourceSets.test.java.exclude '**/Optional*.java'
 } else {
     sourceCompatibility = JavaVersion.VERSION_17
     targetCompatibility = JavaVersion.VERSION_17

src/main/java/org/jilt/internal/AbstractTypeSafeBuilderGenerator.java

@@ -77,6 +77,26 @@ protected final TypeName attributeType(VariableElement attribute) {
             TypeVariableName typeVariableName = (TypeVariableName) ret;
             return this.mangleTypeParameter(typeVariableName);
         }
+        // if this is an entire parameterized type, we need to mangle it
+        if (ret instanceof ParameterizedTypeName) {
+            ParameterizedTypeName parameterizedTypeName = (ParameterizedTypeName) ret;
+            return ParameterizedTypeName.get(parameterizedTypeName.rawType,
+                    this.mangleTypeNameParameters(parameterizedTypeName.typeArguments).toArray(new TypeName[]{}));
+        }
+        return ret;
+    }
+
+    private List<TypeName> mangleTypeNameParameters(List<TypeName> typeArguments) {
+        List<TypeName> ret = new ArrayList<>(typeArguments.size());
+        for (TypeName typeName : typeArguments) {
+            if (typeName instanceof TypeVariableName) {
+                // if this is a type variable, we need to mangle it
+                TypeVariableName typeVariableName = (TypeVariableName) typeName;
+                ret.add(this.mangleTypeParameter(typeVariableName));
+            } else {
+                ret.add(typeName);
+            }
+        }
         return ret;
     }
 

src/test/java/org/jilt/test/OptionalsValueTest.java

@@ -0,0 +1,22 @@
+package org.jilt.test;
+
+import org.jilt.test.data.optionals.OptionalsValue;
+import org.jilt.test.data.optionals.OptionalsValueBuilder;
+import org.junit.Test;
+
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class OptionalsValueTest {
+    @Test
+    public void optional_property_is_always_optional() {
+        OptionalsValue<String, Integer> value = OptionalsValueBuilder.<String, Integer>optionalsValue()
+                .optional(Optional.of("abc"))
+                .t2(33)
+                .build();
+
+        assertThat(value.optional).contains("abc");
+        assertThat(value.t2).isEqualTo(33);
+    }
+}

src/test/java/org/jilt/test/data/optionals/OptionalsValue.java

@@ -0,0 +1,17 @@
+package org.jilt.test.data.optionals;
+
+import org.jilt.Builder;
+import org.jilt.BuilderStyle;
+
+import java.util.Optional;
+
+@Builder(style = BuilderStyle.STAGED)
+public final class OptionalsValue<T1, T2> {
+    public final Optional<T1> optional;
+    public final T2 t2;
+
+    public OptionalsValue(Optional<T1> optional, T2 t2) {
+        this.optional = optional;
+        this.t2 = t2;
+    }
+}