Fix comments causing errors with Java 11

server/src/test/java/org/elasticsearch/search/aggregations/bucket/nested/NestedAggregatorTests.java

@@ -91,7 +91,7 @@ public class NestedAggregatorTests extends AggregatorTestCase {
     private final SeqNoFieldMapper.SequenceIDFields sequenceIDFields = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
 
     /**
-     * For each provided field type, we also register an alias with name <field>-alias.
+     * For each provided field type, we also register an alias with name {@code <field>-alias}.
      */
     @Override
     protected Map<String, MappedFieldType> getFieldAliases(MappedFieldType... fieldTypes) {

server/src/test/java/org/elasticsearch/search/aggregations/bucket/nested/ReverseNestedAggregatorTests.java

@@ -59,7 +59,7 @@ public class ReverseNestedAggregatorTests extends AggregatorTestCase {
     private static final String MAX_AGG_NAME = "maxAgg";
 
     /**
-     * For each provided field type, we also register an alias with name <field>-alias.
+     * For each provided field type, we also register an alias with name {@code <field>-alias}.
      */
     @Override
     protected Map<String, MappedFieldType> getFieldAliases(MappedFieldType... fieldTypes) {

server/src/test/java/org/elasticsearch/search/aggregations/bucket/significant/SignificantTermsAggregatorTests.java

@@ -77,7 +77,7 @@ public class SignificantTermsAggregatorTests extends AggregatorTestCase {
     }
 
     /**
-     * For each provided field type, we also register an alias with name <field>-alias.
+     * For each provided field type, we also register an alias with name {@code <field>-alias}.
      */
     @Override
     protected Map<String, MappedFieldType> getFieldAliases(MappedFieldType... fieldTypes) {

server/src/test/java/org/elasticsearch/search/aggregations/bucket/significant/SignificantTextAggregatorTests.java

@@ -53,7 +53,7 @@ import static org.elasticsearch.search.aggregations.AggregationBuilders.signific
 public class SignificantTextAggregatorTests extends AggregatorTestCase {
 
     /**
-     * For each provided field type, we also register an alias with name <field>-alias.
+     * For each provided field type, we also register an alias with name {@code <field>-alias}.
      */
     @Override
     protected Map<String, MappedFieldType> getFieldAliases(MappedFieldType... fieldTypes) {