feat: add string value of equals operator

core/src/main/kotlin/com/github/inflab/spring/data/mongodb/core/aggregation/search/EqualsSearchOperatorDsl.kt

@@ -72,6 +72,15 @@ class EqualsSearchOperatorDsl {
         document["value"] = value
     }
 
+    /**
+     * Value to query for string, indexed as MongoDB Search token type.
+     *
+     * @param value Value must be a string.
+     */
+    fun value(value: String) {
+        document["value"] = value
+    }
+
     /**
      * The score assigned to matching search term results. Use one of the following options to modify the score:
      *

core/src/test/kotlin/com/github/inflab/spring/data/mongodb/core/aggregation/search/EqualsSearchOperatorDslTest.kt

@@ -168,6 +168,27 @@ internal class EqualsSearchOperatorDslTest : FreeSpec({
                 """.trimIndent(),
             )
         }
+
+        "should build a value by String" {
+            // given
+            val operator = equal {
+                value("stringValue")
+            }
+
+            // when
+            val result = operator.build()
+
+            // then
+            result.shouldBeJson(
+                """
+                {
+                  "equals": {
+                    "value": "stringValue"
+                  }
+                }
+                """.trimIndent(),
+            )
+        }
     }
 
     "score" - {