Helidon 4.x: Parameters.first(String) generates java.lang.IndexOutOfB…

common/parameters/src/main/java/io/helidon/common/parameters/ParametersMap.java

@@ -97,8 +97,9 @@ public String toString() {
 
     @Override
     public OptionalValue<String> first(String name) {
-        if (contains(name)) {
-            return OptionalValue.create(mapperManager, name, get(name), GenericType.STRING, qualifiers);
+        List<String> value = params.get(name);
+        if (value != null && !value.isEmpty()) {
+            return OptionalValue.create(mapperManager, name, value.get(0), GenericType.STRING, qualifiers);
         }
         return OptionalValue.create(mapperManager, name, GenericType.STRING, qualifiers);
     }

common/parameters/src/test/java/io/helidon/common/parameters/ParametersTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,13 @@
 
 package io.helidon.common.parameters;
 
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 
+import io.helidon.common.mapper.OptionalValue;
+
 import org.junit.jupiter.api.Test;
 
 import static org.hamcrest.CoreMatchers.containsString;
@@ -35,6 +38,7 @@ class ParametersTest {
     @Test
     void testEmpty() {
         Parameters empty = Parameters.empty(UNIT_TEST);
+        assertThat(empty.first(UNIT_TEST).isEmpty(), is(true));
         assertThat(empty.component(), is(UNIT_TEST));
         assertThat("Empty parameters should not contain anything", empty.contains("anything"), is(false));
         assertThat("Empty parameters should have size 0", empty.size(), is(0));
@@ -111,4 +115,13 @@ void testBuilder() {
         assertThat(params.toString(), containsString(UNIT_TEST));
         assertThat("Parameters should not be empty", params.isEmpty(), is(false));
     }
+
+    @Test
+    void issue8710() {
+        Map<String, List<String>> params = new HashMap<>();
+        params.put("param", List.of());
+        Parameters parameters = Parameters.create("test", params);
+        OptionalValue<String> value = parameters.first("param");
+        assertThat(value.isEmpty(), is(true));
+    }
 }

common/uri/src/main/java/io/helidon/common/uri/UriQueryImpl.java

@@ -148,11 +148,11 @@ public String get(String name) throws NoSuchElementException {
     public OptionalValue<String> first(String name) {
         ensureDecoded();
         List<String> values = decodedQueryParams.get(name);
-        if (values == null) {
+        if (values == null || values.isEmpty()) {
             return OptionalValue.create(MapperManager.global(), name, GenericType.STRING, "uri", "query");
         }
-        String value = values.isEmpty() ? "" : values.iterator().next();
-        return OptionalValue.create(MapperManager.global(), name, value, GenericType.STRING, "uri", "query");
+        return OptionalValue.create(MapperManager.global(), name, values.iterator().next(),
+                GenericType.STRING, "uri", "query");
     }
 
     @Override

common/uri/src/test/java/io/helidon/common/uri/UriQueryTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@
 import java.net.URI;
 import java.net.URLEncoder;
 
+import io.helidon.common.mapper.OptionalValue;
+
 import org.junit.jupiter.api.Test;
 
 import static java.nio.charset.StandardCharsets.US_ASCII;
@@ -72,4 +74,16 @@ void testNullQueryFails() {
     void testNullUriFails() {
         assertThrows(NullPointerException.class, () -> UriQuery.create((URI) null));
     }
+
+    @Test
+    void issue8710() {
+        UriQuery uriQuery = UriQuery.create(URI.create("http://foo/bar?a&b=c"));
+        OptionalValue<String> optional = uriQuery.first("a");
+        assertThat(optional.isEmpty(), is(true));
+
+        assertThat(uriQuery.all("a"), hasItems());
+        assertThat(uriQuery.all("b"), hasItems("c"));
+        assertThat(uriQuery.getRaw("a"), is(""));
+    }
+
 }

webclient/tests/webclient/src/test/java/io/helidon/webclient/tests/FormTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2020, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -93,6 +93,7 @@ public void testFormContent() {
             assertThat(received.all(SPECIAL, List::of), is(ADVANCED_TEST_FORM.all(SPECIAL)));
             assertThat(received.all(MULTIPLE), is(ADVANCED_TEST_FORM.all(MULTIPLE)));
             assertThat(received.all(NO_VALUE).size(), is(0));
+            assertThat(received.first(NO_VALUE).isEmpty(), is(true));
         }
     }
 }