OutputDir no longer accepts null constructor param.

api/src/main/groovy/com/jessebrault/ssg/SimpleBuildTasksConverter.groovy

@@ -12,7 +12,7 @@ final class SimpleBuildTasksConverter implements BuildTasksConverter {
     Result<Collection<Task>> convert(Build build) {
         def taskSpec = new TaskSpec(
                 build.name,
-                build.outputDirFunction.apply(build).file,
+                build.outputDirFunction.apply(build).asFile(),
                 build.siteSpec,
                 build.globals
         )

api/src/main/groovy/com/jessebrault/ssg/buildscript/OutputDir.groovy

@@ -1,24 +1,41 @@
 package com.jessebrault.ssg.buildscript
 
 import groovy.transform.EqualsAndHashCode
-import org.jetbrains.annotations.Nullable
+import groovy.transform.NullCheck
 
+@NullCheck
 @EqualsAndHashCode
 final class OutputDir {
 
-    @Nullable
     final String path
 
-    OutputDir(@Nullable String path) {
+    OutputDir(String path) {
         this.path = path
     }
 
     OutputDir(File file) {
-        this.path = file.path
+        this(file.path)
     }
 
-    File getFile() {
-        this.path ? new File(this.path) : new File('')
+    File asFile() {
+        new File(this.path)
+    }
+
+    String asString() {
+        this.path
+    }
+
+    Object asType(Class<?> clazz) {
+        switch (clazz) {
+            case File -> this.asFile()
+            case String -> this.asString()
+            default -> throw new IllegalArgumentException('cannot cast to a class other than File or String')
+        }
+    }
+
+    @Override
+    String toString() {
+        "OutputDir(path: ${ this.path })"
     }
 
 }

api/src/main/groovy/com/jessebrault/ssg/buildscript/OutputDirFunctions.groovy

@@ -1,7 +1,5 @@
 package com.jessebrault.ssg.buildscript
 
-import org.jetbrains.annotations.Nullable
-
 import java.util.function.Function
 
 final class OutputDirFunctions {
@@ -19,7 +17,7 @@ final class OutputDirFunctions {
         return { new OutputDir(dir) }
     }
 
-    static Function<Build, OutputDir> of(@Nullable String path) {
+    static Function<Build, OutputDir> of(String path) {
         return { new OutputDir(path) }
     }
 

api/src/main/groovy/com/jessebrault/ssg/buildscript/dsl/BuildDelegate.groovy

@@ -3,7 +3,6 @@ package com.jessebrault.ssg.buildscript.dsl
 import com.jessebrault.ssg.buildscript.Build
 import com.jessebrault.ssg.buildscript.OutputDir
 import com.jessebrault.ssg.buildscript.OutputDirFunctions
-import org.jetbrains.annotations.Nullable
 
 import java.util.function.Function
 
@@ -31,7 +30,7 @@ final class BuildDelegate extends AbstractBuildDelegate<Build> {
         this.outputDirFunction = OutputDirFunctions.of(file)
     }
 
-    void setOutputDir(@Nullable String path) {
+    void setOutputDir(String path) {
         this.outputDirFunction = OutputDirFunctions.of(path)
     }