Proxy endpoint certificate secrets through EndpointCertificateSecretStore

2 files changed, 34 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/stream/CustomCollectors.java b/vespajlib/src/main/java/com/yahoo/stream/CustomCollectors.java
index 9076846bbf4..c6868fb28f6 100644
--- a/vespajlib/src/main/java/com/yahoo/stream/CustomCollectors.java
+++ b/vespajlib/src/main/java/com/yahoo/stream/CustomCollectors.java
@@ -3,6 +3,7 @@ package com.yahoo.stream;
 
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -70,6 +71,22 @@ public class CustomCollectors {
         return Collectors.toMap(keyMapper, valueMapper, throwingMerger(), mapSupplier);
     }
 
+    /**
+     * Returns a {@code Collector} that returns a singleton, or throws an {@code IllegalArgumentException} if there are more than one item.
+     *
+     * @return A collector returning an optional element
+     * @param <T> Type of the input elements.
+     * @throws IllegalArgumentException if there are more than one element
+     */
+    public static <T> Collector<T, ?, Optional<T>> singleton() {
+        return Collectors.collectingAndThen(
+                Collectors.toList(),
+                list -> {
+                    if (list.size() > 1) throw new IllegalArgumentException("More than one element");
+                    return list.stream().findAny();
+                }
+        );
+    }
 
     private static <T> BinaryOperator<T> throwingMerger() {
         return (u,v) -> { throw new DuplicateKeyException(u); };
diff --git a/vespajlib/src/test/java/com/yahoo/stream/CustomCollectorsTest.java b/vespajlib/src/test/java/com/yahoo/stream/CustomCollectorsTest.java
index fcafb4c6152..880e57683f8 100644
--- a/vespajlib/src/test/java/com/yahoo/stream/CustomCollectorsTest.java
+++ b/vespajlib/src/test/java/com/yahoo/stream/CustomCollectorsTest.java
@@ -7,12 +7,14 @@ import org.junit.Test;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.Function;
 
 import static com.yahoo.stream.CustomCollectors.toCustomMap;
 import static com.yahoo.stream.CustomCollectors.toLinkedMap;
 import static java.util.function.Function.identity;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.fail;
 
 /**
@@ -51,6 +53,21 @@ public class CustomCollectorsTest {
         }
     }
 
+    @Test
+    public void singleton_collector_throws_when_multiple() {
+        List<String> items = List.of("foo1", "bar", "foo2");
+        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class,
+                () -> items.stream().filter(s -> s.startsWith("foo")).collect(CustomCollectors.singleton()));
+        assertEquals("More than one element", exception.getMessage());
+    }
+
+    @Test
+    public void collector_returns_singleton() {
+        List<String> items = List.of("foo1", "bar", "foo2");
+        Optional<String> bar = items.stream().filter(s -> s.startsWith("bar")).collect(CustomCollectors.singleton());
+        assertEquals(Optional.of("bar"), bar);
+    }
+
     private static List<String> numberList() {
         return List.of("zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten");
     }