Add substitutions for DriverFactory#getOrCreateMetricsProvider. (#1183)

This prevents an eager class loading of Micrometer when compiling on GraalVM native image and fixes #1182.

driver/src/main/java/org/neo4j/driver/internal/svm/MicrometerSubstitutions.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Licensed 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.neo4j.driver.internal.svm;
+
+import com.oracle.svm.core.annotate.Substitute;
+import com.oracle.svm.core.annotate.TargetClass;
+
+import org.neo4j.driver.Config;
+import org.neo4j.driver.MetricsAdapter;
+import org.neo4j.driver.internal.DriverFactory;
+import org.neo4j.driver.internal.metrics.DevNullMetricsProvider;
+import org.neo4j.driver.internal.metrics.InternalMetricsProvider;
+import org.neo4j.driver.internal.metrics.MetricsProvider;
+import org.neo4j.driver.internal.metrics.MicrometerMetricsProvider;
+import org.neo4j.driver.internal.util.Clock;
+
+@TargetClass( DriverFactory.class )
+final class Target_org_neo4j_driver_internal_DriverFactory
+{
+
+    /**
+     * Substitutes metrics adatper in such a way that it falls back to off when Micrometer is not available.
+     *
+     * @param config Drivers config
+     * @param clock Clock to use
+     * @return A metrics provider, never null
+     */
+    @Substitute
+    protected static MetricsProvider getOrCreateMetricsProvider( Config config, Clock clock )
+    {
+        MetricsAdapter metricsAdapter = config.metricsAdapter();
+        if ( metricsAdapter == null )
+        {
+            metricsAdapter = config.isMetricsEnabled() ? MetricsAdapter.DEFAULT : MetricsAdapter.DEV_NULL;
+        }
+        switch ( metricsAdapter )
+        {
+        case DEV_NULL:
+            return DevNullMetricsProvider.INSTANCE;
+        case DEFAULT:
+            return new InternalMetricsProvider( clock, config.logging() );
+        case MICROMETER:
+            try
+            {
+                @SuppressWarnings( "unused" ) Class<?> metricsClass = Class.forName( "io.micrometer.core.instrument.Metrics" );
+                return MicrometerMetricsProvider.forGlobalRegistry();
+            }
+            catch ( ClassNotFoundException e )
+            {
+                return DevNullMetricsProvider.INSTANCE;
+            }
+        }
+        throw new IllegalStateException( "Unknown or unsupported MetricsAdapter: " + metricsAdapter );
+    }
+}
+
+class MicrometerSubstitutions
+{
+}