Cleaned up OutputDir and OutputDirFunctions.

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

@@ -6,10 +6,6 @@ import org.jetbrains.annotations.Nullable
 @EqualsAndHashCode
 final class OutputDir {
 
-    static OutputDir concat(OutputDir od0, OutputDir od1) {
-        new OutputDir(od1.path ? od1.path : od0.path)
-    }
-
     @Nullable
     final String path
 
@@ -25,8 +21,4 @@ final class OutputDir {
         this.path ? new File(this.path) : new File('')
     }
 
-    OutputDir plus(OutputDir other) {
-        concat(this, other)
-    }
-
 }

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

@@ -2,6 +2,7 @@ package com.jessebrault.ssg.buildscript
 
 import groovy.transform.stc.ClosureParams
 import groovy.transform.stc.SimpleType
+import org.jetbrains.annotations.Nullable
 
 import java.util.function.Function
 
@@ -27,7 +28,7 @@ final class OutputDirFunctions {
         of { new OutputDir(dir) }
     }
 
-    static Function<Build, OutputDir> of(String path) {
+    static Function<Build, OutputDir> of(@Nullable String path) {
         of { new OutputDir(path) }
     }
 

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

@@ -28,11 +28,11 @@ final class BuildDelegate extends AbstractBuildDelegate<Build> {
     }
 
     void setOutputDir(File file) {
-        this.outputDirFunction = { new OutputDir(file) }
+        this.outputDirFunction = OutputDirFunctions.of(file)
     }
 
     void setOutputDir(@Nullable String path) {
-        this.outputDirFunction = { new OutputDir(path) }
+        this.outputDirFunction = OutputDirFunctions.of(path)
     }
 
 }