Support optional 'path' config type

Initial work needed for this to work (config definition and config library)

1 files changed, 19 insertions, 1 deletions

diff --git a/config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java b/config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java
index e86b13b2c98..0dbc40a246c 100644
--- a/config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java
+++ b/config/src/main/java/com/yahoo/vespa/config/ConfigPayloadApplier.java
@@ -21,6 +21,7 @@ import java.util.Deque;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.logging.Logger;
 
@@ -213,7 +214,10 @@ public class ConfigPayloadApplier<T extends ConfigInstance.Builder> {
         Inspector value = (Inspector)rawValue;
         if (isPathField(builder, methodName))
             return resolvePath(value.asString());
-        else if (isUrlField(builder, methodName))
+        if (isOptionalPathField(builder, methodName)) {
+            String v = value.asString();
+            return resolvePath(v.isEmpty() ? Optional.empty() : Optional.of(v));
+        } else if (isUrlField(builder, methodName))
             return value.asString().isEmpty() ? "" : resolveUrl(value.asString());
         else if (isModelField(builder, methodName))
             return value.asString().isEmpty() ? "" : resolveModel(value.asString());
@@ -234,6 +238,10 @@ public class ConfigPayloadApplier<T extends ConfigInstance.Builder> {
         return new FileReference(path.toString());
     }
 
+    private Optional<FileReference> resolvePath(Optional<String> value) {
+        return value.isEmpty() ? Optional.empty() : Optional.of(resolvePath(value.get()));
+    }
+
     private UrlReference resolveUrl(String url) {
         if ( ! isClientside()) return new UrlReference(url);
         File file = urlDownloader.waitFor(new UrlReference(url), 60 * 60);
@@ -319,6 +327,16 @@ public class ConfigPayloadApplier<T extends ConfigInstance.Builder> {
         return isFieldType(pathFieldSet, builder, methodName, FileReference.class);
     }
 
+    /**
+     * Checks if this field is of type 'path', in which
+     * case some special handling might be needed. Caches the result.
+     */
+    private final Set<String> optionalPathFieldSet = new HashSet<>();
+    private boolean isOptionalPathField(Object builder, String methodName) {
+        // Paths are stored as Optional<FileReference> in Builder.
+        return isFieldType(optionalPathFieldSet, builder, methodName, Optional.class);
+    }
+
     private final Set<String> urlFieldSet = new HashSet<>();
     private boolean isUrlField(Object builder, String methodName) {
         // Urls are stored as UrlReference in Builder.