replace Map with ConcurrentMap for lazy loading

Signed-off-by: Samir Romdhani <samir.romdhani_externe@rte-france.com>

Author: samirromdhani

iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/NetworkSerDe.java

@@ -56,6 +56,8 @@
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.ForkJoinPool;
 import java.util.function.Supplier;
@@ -89,7 +91,7 @@ public final class NetworkSerDe {
     static final byte[] BIIDM_MAGIC_NUMBER = {0x42, 0x69, 0x6e, 0x61, 0x72, 0x79, 0x20, 0x49, 0x49, 0x44, 0x4d};
 
     private static final Supplier<Schema> DEFAULT_SCHEMA_SUPPLIER = Suppliers.memoize(() -> NetworkSerDe.createSchema(DefaultExtensionsSupplier.getInstance()));
-    private static final Supplier<Map<IidmVersion, Schema>> DEFAULT_SCHEMAS_SUPPLIER = Suppliers.memoize(() -> NetworkSerDe.createDefaultSchemas(DefaultExtensionsSupplier.getInstance()));
+    private static final Supplier<ConcurrentMap<IidmVersion, Schema>> DEFAULT_SCHEMAS_SUPPLIER = Suppliers.memoize(ConcurrentHashMap::new);
     private static final int MAX_NAMESPACE_PREFIX_NUM = 100;
     private static final String XSD_RESOURCE_DIR = "/xsd/";
 
@@ -177,10 +179,7 @@ private static void validate(InputStream is, IidmVersion version, ExtensionsSupp
         // XSD validation
         Schema schema;
         if (extensionsSupplier == DefaultExtensionsSupplier.getInstance()) {
-            schema = DEFAULT_SCHEMAS_SUPPLIER.get().get(version);
-            if (schema == null) {
-                throw new PowsyblException("Schema not found: version=" + version);
-            }
+            schema = DEFAULT_SCHEMAS_SUPPLIER.get().computeIfAbsent(version, v -> createSchema(DefaultExtensionsSupplier.getInstance(), v));
         } else {
             schema = createSchema(extensionsSupplier, version);
         }
@@ -193,15 +192,6 @@ private static void validate(InputStream is, IidmVersion version, ExtensionsSupp
         }
     }
 
-    private static Map<IidmVersion, Schema> createDefaultSchemas(ExtensionsSupplier extensionsSupplier) {
-        Map<IidmVersion, Schema> schemasByIIdmVersion = new EnumMap<>(IidmVersion.class);
-        for (IidmVersion version : IidmVersion.values()) {
-            Schema schema = createSchema(extensionsSupplier, version);
-            schemasByIIdmVersion.put(version, schema);
-        }
-        return schemasByIIdmVersion;
-    }
-
     private static Schema createSchema(ExtensionsSupplier extensionsSupplier, IidmVersion version) {
         Objects.requireNonNull(extensionsSupplier);
         Objects.requireNonNull(version);