diff --git a/.github/workflows/gradle.yml b/.github/workflows/gradle.yml
index 0885752..a82951a 100644
--- a/.github/workflows/gradle.yml
+++ b/.github/workflows/gradle.yml
@@ -17,8 +17,6 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-    permissions:
-      contents: read
 
     steps:
     - uses: actions/checkout@v4
diff --git a/build.gradle b/build.gradle
index 73e520c..57426b8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,6 +1,5 @@
 plugins {
     id 'java'
-    id 'org.jetbrains.kotlin.jvm'
 }
 
 group = 'org.latwal.vivek'
@@ -19,12 +18,8 @@ dependencies {
 
     testImplementation platform('org.junit:junit-bom:5.10.0')
     testImplementation 'org.junit.jupiter:junit-jupiter'
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
 }
 
 test {
     useJUnitPlatform()
 }
-kotlin {
-    jvmToolchain(17)
-}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..a4b76b9
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..df97d72
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.10.2-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 1b6c787..f5feea6 100644
--- a/gradlew
+++ b/gradlew
@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +82,12 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s
+' "$PWD" ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,22 +134,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,11 +201,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
@@ -205,6 +217,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
 # Use "xargs" to parse quoted args.
 #
 # With -n1 it outputs one arg per line, with the quotes and backslashes removed.
diff --git a/gradlew.bat b/gradlew.bat
index 107acd3..9d21a21 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -13,8 +13,10 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 @rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +27,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,13 +43,13 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -56,11 +59,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -75,13 +78,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal
diff --git a/src/main/java/org/latwal/vivek/src/parser/Evaluator.java b/src/main/java/org/latwal/vivek/src/parser/Evaluator.java
index 900a1b8..3f1c9d5 100644
--- a/src/main/java/org/latwal/vivek/src/parser/Evaluator.java
+++ b/src/main/java/org/latwal/vivek/src/parser/Evaluator.java
@@ -18,8 +18,11 @@ JsonNode evaluateTokenMappingSpecs(JsonNode mappingSpecs , JsonNode inputNode) {
         if(mappingIsPathMapping(mappingSpecs)){
             String inputPath = JsonNodeUtils.getAtPathELseThrow(mappingSpecs,"/path").textValue();
             return JsonNodeUtils.getAtPath(inputNode,inputPath);
-        } else if (mappingIsFunctionalMapping(mappingSpecs)) {
+        } else if (mappingIsFunction(mappingSpecs)) {
             return evaluateFunction(mappingSpecs,inputNode);
+        } else if(mappingIfFunctionSpecs(mappingSpecs)){
+            JsonNode functionBody = JsonNodeUtils.getOrThrow(mappingSpecs, "function_body");
+            return evaluateFunction(functionBody, inputNode);
         } else {
             throw new IllegalArgumentException("unsupported mapping specs , cannot successfully extract the type of specs from the json");
         }
@@ -29,10 +32,14 @@ boolean mappingIsPathMapping(JsonNode mappingSpecs) {
        return mappingSpecs.has("path");
     }
 
-    boolean mappingIsFunctionalMapping(JsonNode mappingSpecs) {
+    boolean mappingIsFunction(JsonNode mappingSpecs) {
         return mappingSpecs.has("function_name");
     }
 
+    boolean mappingIfFunctionSpecs(JsonNode mappingSpecs) {
+        return mappingSpecs.has("function_body");
+    }
+
     JsonNode evaluateFunction(JsonNode functionMappingSpecs , JsonNode inputNode) {
         String functionName = JsonNodeUtils.getOrThrow(functionMappingSpecs, "function_name").textValue();
         switch (functionName){
diff --git a/src/main/java/org/latwal/vivek/src/token/FunctionalTokenMapperData.java b/src/main/java/org/latwal/vivek/src/token/FunctionalTokenMapperData.java
index f49f9c9..f9dd72a 100644
--- a/src/main/java/org/latwal/vivek/src/token/FunctionalTokenMapperData.java
+++ b/src/main/java/org/latwal/vivek/src/token/FunctionalTokenMapperData.java
@@ -4,12 +4,10 @@
 import org.latwal.vivek.src.support.JsonNodeUtils;
 
 class FunctionalTokenMapperData extends MapperToken {
-    String functionName;
 
     FunctionalTokenMapperData(JsonNode mapperInfo) {
         super(JsonNodeUtils.getOrThrow(mapperInfo, "mapping_spec"));
         JsonNode mappings = this.mappingSpecs;
-        this.functionName = mappings.get("function_name").asText();
     }
 
 }
\ No newline at end of file
diff --git a/src/test/resources/jsons/mapper.json b/src/test/resources/jsons/mapper.json
index 77a4584..881507b 100644
--- a/src/test/resources/jsons/mapper.json
+++ b/src/test/resources/jsons/mapper.json
@@ -21,19 +21,27 @@
       "operationType": "function",
       "pathToMap": "/name/full_name",
       "mapping_spec": {
-        "function_name": "concat",
-        "args": {
-          "values": [
-            {
-              "function_name": "uppercase",
-              "args": {
-                "value": { "path": "/name/fn"}
+        "function_body": {
+          "function_name": "concat",
+          "args": {
+            "values": [
+              {
+                "function_name": "uppercase",
+                "args": {
+                  "value": {
+                    "path": "/name/fn"
+                  }
+                }
+              },
+              {
+                "path": "/name/mn"
+              },
+              {
+                "path": "/name/ln"
               }
-            },
-            { "path": "/name/mn" },
-            { "path": "/name/ln" }
-          ],
-          "separator": " "
+            ],
+            "separator": " "
+          }
         }
       }
     }