Fix typo in SchemaMappingInspector Javadoc

Closes gh-1195

Signed-off-by: Alexander Münch <[email protected]>

Author: theHacker

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

@@ -123,7 +123,7 @@ private SchemaMappingInspector(
 
 	/**
 	 * Perform an inspection and create a {@link SchemaReport}.
-	 * The inspection is one once only, during the first call to this method.
+	 * The inspection is done once only, during the first call to this method.
 	 */
 	public SchemaReport getOrCreateReport() {
 		if (this.report == null) {