Set start of the week to Monday for root locale using SPI

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -836,6 +836,12 @@ class BuildPlugin implements Plugin<Project> {
                     if ((ext.get('runtimeJavaVersion') as JavaVersion) >= JavaVersion.VERSION_1_9) {
                         test.jvmArgs '--illegal-access=warn'
                     }
+                    if ((ext.get('runtimeJavaVersion') as JavaVersion) == JavaVersion.VERSION_1_8) {
+                        test.systemProperty ('java.locale.providers','SPI,JRE')
+                    } else if ((ext.get('runtimeJavaVersion') as JavaVersion) >= JavaVersion.VERSION_1_9) {
+                        test.systemProperty ('java.locale.providers','SPI,COMPAT')
+                    }
+
                 }
 
                 test.jvmArgumentProviders.add(nonInputProperties)

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/RestIntegTestTask.groovy

@@ -24,6 +24,7 @@ import org.elasticsearch.gradle.testclusters.RestTestRunnerTask
 import org.elasticsearch.gradle.testclusters.TestClustersPlugin
 import org.elasticsearch.gradle.tool.ClasspathUtils
 import org.gradle.api.DefaultTask
+import org.gradle.api.JavaVersion
 import org.gradle.api.Task
 import org.gradle.api.execution.TaskExecutionAdapter
 import org.gradle.api.logging.Logger

distribution/src/config/jvm.options

@@ -114,6 +114,9 @@ ${error.file}
 
 # JDK 9+ GC logging
 9-:-Xlog:gc*,gc+age=trace,safepoint:file=${loggc}:utctime,pid,tags:filecount=32,filesize=64m
+
+# CalendarDataProvider is being customized to ISO standard, SPI has to be first provider.
+8:-Djava.locale.providers=SPI,JRE
 # due to internationalization enhancements in JDK 9 Elasticsearch need to set the provider to COMPAT otherwise
 # time/date parsing will break in an incompatible way for some date patterns and locals
-9-:-Djava.locale.providers=COMPAT
+9-:-Djava.locale.providers=SPI,COMPAT

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/310_date_agg_per_day_of_week.yml

@@ -0,0 +1,47 @@
+---
+setup:
+  - skip:
+      version: " - 7.3.99"
+      reason:  "only backported to 7.4 (7x)"
+
+  - do:
+        indices.create:
+          index: test
+          body:
+              mappings:
+                properties:
+                  date:
+                    type: date
+
+  - do:
+      index:
+        index: test
+        id:    1
+        body:  { "date": "2009-11-15T14:12:12" }
+
+  - do:
+      indices.refresh:
+        index: [test]
+
+---
+# The inserted document has a field date=2009-11-15T14:12:12 which is Sunday.
+# When aggregating per day of the week this should be considered as last day of the week (7)
+# and this value should be used in 'key_as_string'
+"Date aggregartion per day of week":
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: test
+        body:
+          aggregations:
+            test:
+              "date_histogram": {
+                "field": "date",
+                "calendar_interval": "day",
+                "format": "e",
+                "offset": 0
+              }
+
+  - match: {hits.total: 1}
+  - length: { aggregations.test.buckets: 1 }
+  - match: { aggregations.test.buckets.0.key_as_string: "7" }

server/src/main/java/org/elasticsearch/common/time/IsoCalendarDataProvider.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.common.time;
+
+import java.util.Calendar;
+import java.util.Locale;
+import java.util.spi.CalendarDataProvider;
+
+public class IsoCalendarDataProvider extends CalendarDataProvider {
+
+    @Override
+    public int getFirstDayOfWeek(Locale locale) {
+        return Calendar.MONDAY;
+    }
+
+    @Override
+    public int getMinimalDaysInFirstWeek(Locale locale) {
+        return 4;
+    }
+
+    @Override
+    public Locale[] getAvailableLocales() {
+        return new Locale[]{Locale.ROOT};
+    }
+}

server/src/main/resources/META-INF/services/java.util.spi.CalendarDataProvider

@@ -0,0 +1 @@
+org.elasticsearch.common.time.IsoCalendarDataProvider

server/src/test/java/org/elasticsearch/common/joda/JavaJodaTimeDuellingTests.java

@@ -28,6 +28,7 @@
 import org.joda.time.format.ISODateTimeFormat;
 import org.joda.time.format.DateTimeFormat;
 
+import java.time.LocalDateTime;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
@@ -39,6 +40,28 @@
 import static org.hamcrest.Matchers.is;
 
 public class JavaJodaTimeDuellingTests extends ESTestCase {
+    @Override
+    protected boolean enableWarningsCheck() {
+        return false;
+    }
+
+    public void testDayOfWeek() {
+        //7 (ok joda) vs 1 (java by default) but 7 with customized org.elasticsearch.common.time.IsoLocale.ISO8601
+        ZonedDateTime now = LocalDateTime.of(2009,11,15,1,32,8,328402)
+                                         .atZone(ZoneOffset.UTC); //Sunday
+        DateFormatter jodaFormatter = Joda.forPattern("e").withLocale(Locale.ROOT).withZone(ZoneOffset.UTC);
+        DateFormatter javaFormatter = DateFormatter.forPattern("8e").withZone(ZoneOffset.UTC);
+        assertThat(jodaFormatter.format(now), equalTo(javaFormatter.format(now)));
+    }
+
+    public void testStartOfWeek() {
+        //2019-21 (ok joda) vs 2019-22 (java by default) but 2019-21 with customized org.elasticsearch.common.time.IsoLocale.ISO8601
+        ZonedDateTime now = LocalDateTime.of(2019,5,26,1,32,8,328402)
+                                         .atZone(ZoneOffset.UTC);
+        DateFormatter jodaFormatter = Joda.forPattern("xxxx-ww").withLocale(Locale.ROOT).withZone(ZoneOffset.UTC);
+        DateFormatter javaFormatter = DateFormatter.forPattern("8YYYY-ww").withZone(ZoneOffset.UTC);
+        assertThat(jodaFormatter.format(now), equalTo(javaFormatter.format(now)));
+    }
 
     //these parsers should allow both ',' and '.' as a decimal point
     public void testDecimalPointParsing(){