Log schema resources during application startup

This commit logs the number of schema resources that were loaded to
create the GraphQL schema, at the INFO level. If DEBUG is enabled for
this package, the description of all schema resources will be logged as
well.

Closes gh-566

Author: bclozel

spring-graphql/src/main/java/org/springframework/graphql/execution/DefaultSchemaResourceGraphQlSourceBuilder.java

@@ -24,6 +24,7 @@
 import java.util.List;
 import java.util.Set;
 import java.util.function.BiFunction;
+import java.util.stream.Collectors;
 
 import graphql.language.InterfaceTypeDefinition;
 import graphql.language.UnionTypeDefinition;
@@ -36,6 +37,8 @@
 import graphql.schema.idl.SchemaParser;
 import graphql.schema.idl.TypeDefinitionRegistry;
 import graphql.schema.idl.WiringFactory;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 
 import org.springframework.core.io.Resource;
 import org.springframework.lang.Nullable;
@@ -53,6 +56,8 @@ final class DefaultSchemaResourceGraphQlSourceBuilder
 		extends AbstractGraphQlSourceBuilder<GraphQlSource.SchemaResourceBuilder>
 		implements GraphQlSource.SchemaResourceBuilder {
 
+	private static final Log logger = LogFactory.getLog(DefaultSchemaResourceGraphQlSourceBuilder.class);
+
 	private final Set<Resource> schemaResources = new LinkedHashSet<>();
 
 	private final List<RuntimeWiringConfigurer> runtimeWiringConfigurers = new ArrayList<>();
@@ -98,6 +103,14 @@ protected GraphQLSchema initGraphQlSchema() {
 				.reduce(TypeDefinitionRegistry::merge)
 				.orElseThrow(MissingSchemaException::new);
 
+		logger.info("Loaded " + this.schemaResources.size() + " resource(s) in the GraphQL schema.");
+		if (logger.isDebugEnabled()) {
+			String resources = this.schemaResources.stream()
+					.map(Resource::getDescription)
+					.collect(Collectors.joining(","));
+			logger.debug("Loaded GraphQL schema resources: (" + resources + ")");
+		}
+
 		RuntimeWiring runtimeWiring = initRuntimeWiring();
 
 		TypeResolver typeResolver = initTypeResolver();