Optimize error message

Signed-off-by: Gao Binlong <[email protected]>

Author: gaobinlong

rest-api-spec/src/main/resources/rest-api-spec/test/index/120_field_name.yml

@@ -9,7 +9,7 @@
         index:    test_1
 
   - do:
-      catch: /field name cannot contain only dot/
+      catch: /field name cannot contain only the character \[.\]/
       index:
         index:   test_1
         id:      1
@@ -18,7 +18,7 @@
         }
 
   - do:
-      catch: /field name cannot contain only dot/
+      catch: /field name cannot contain only the character \[.\]/
       index:
         index:   test_1
         id:      1
@@ -27,7 +27,7 @@
         }
 
   - do:
-      catch: /field name cannot contain only dot/
+      catch: /field name cannot contain only the character \[.\]/
       index:
         index:   test_1
         id:      1

server/src/main/java/org/opensearch/index/mapper/DocumentParser.java

@@ -207,7 +207,7 @@ private static String[] splitAndValidatePath(String fullFieldPath) {
         if (fullFieldPath.contains(".")) {
             String[] parts = fullFieldPath.split("\\.");
             if (parts.length == 0) {
-                throw new IllegalArgumentException("field name cannot contain only dot");
+                throw new IllegalArgumentException("field name cannot contain only the character [.]");
             }
             for (String part : parts) {
                 if (Strings.hasText(part) == false) {

server/src/test/java/org/opensearch/index/mapper/DocumentParserTests.java

@@ -1716,20 +1716,20 @@ public void testDynamicFieldsWithOnlyDot() throws Exception {
         })));
 
         assertThat(e.getCause(), notNullValue());
-        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only dot"));
+        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only the character [.]"));
 
         e = expectThrows(
             MapperParsingException.class,
             () -> mapper.parse(source(b -> { b.startObject("..").field("foo", 2).endObject(); }))
         );
 
         assertThat(e.getCause(), notNullValue());
-        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only dot"));
+        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only the character [.]"));
 
         e = expectThrows(MapperParsingException.class, () -> mapper.parse(source(b -> b.field(".", "1234"))));
 
         assertThat(e.getCause(), notNullValue());
-        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only dot"));
+        assertThat(e.getCause().getMessage(), containsString("field name cannot contain only the character [.]"));
     }
 
     public void testDynamicFieldsEmptyName() throws Exception {