From 19a8afe05f1c12f95aeb28eef41284d1c590be6f Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Wed, 30 Jul 2025 11:49:48 +0200
Subject: [PATCH 1/6] fix: hidden property without value should be deprecated

Closes #181
---
 .../src/defs/properties.json                  | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/packages/zeebe-element-templates-json-schema/src/defs/properties.json b/packages/zeebe-element-templates-json-schema/src/defs/properties.json
index 896f0e8..704b386 100644
--- a/packages/zeebe-element-templates-json-schema/src/defs/properties.json
+++ b/packages/zeebe-element-templates-json-schema/src/defs/properties.json
@@ -627,6 +627,45 @@
       },
       {
         "$ref": "./properties/taskSchedule.json"
+      },
+      {
+        "if": {
+          "properties": {
+            "type": {
+              "const": "Hidden"
+            },
+            "binding": {
+            "properties": {
+              "type": { 
+                "not": {
+                "const": "zeebe:userTask" 
+                }
+              }
+            },
+            "required": [
+              "type"
+            ]
+          }
+          },
+          "required": [
+            "type"
+          ]
+        },
+        "then": {
+          "anyOf": [
+            { "required": [ "value" ] },
+            { "required": [ "generatedValue" ] },
+            {
+              "not": {
+                "anyOf": [
+                  { "required": [ "value" ] },
+                  { "required": [ "generatedValue" ] }
+                ]
+              },
+              "deprecated": true
+            }
+          ]
+        }
       }
     ],
     "properties": {

From 1fc65b614291140346f7b9ab4d22d9193ffcd124 Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Wed, 30 Jul 2025 12:09:38 +0200
Subject: [PATCH 2/6] test: hidden property without value should be deprecated

---
 .../test/fixtures/hidden-property.js          | 29 +++++++++++++++++++
 .../test/fixtures/hidden-zeebe-user-task.js   | 22 ++++++++++++++
 .../test/spec/validationSpec.js               |  6 ++++
 3 files changed, 57 insertions(+)
 create mode 100644 packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
 create mode 100644 packages/zeebe-element-templates-json-schema/test/fixtures/hidden-zeebe-user-task.js

diff --git a/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
new file mode 100644
index 0000000..1ba89ba
--- /dev/null
+++ b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
@@ -0,0 +1,29 @@
+export const template = {
+  'name': 'HiddenProperty',
+  'id': 'com.camunda.example.HiddenProperty',
+  'appliesTo': [
+    'bpmn:Task'
+  ],
+  'elementType': {
+    'value': 'bpmn:BusinessRuleTask'
+  },
+  'properties': [
+    {
+      'type': 'Hidden',
+      'value': 'decision',
+      'binding': {
+        'type': 'zeebe:calledDecision',
+        'property': 'decisionId'
+      }
+    },
+    {
+      'type': 'Hidden',
+      'binding': {
+        'type': 'zeebe:calledDecision',
+        'property': 'resultVariable'
+      }
+    }
+  ]
+};
+
+export const errors = null;
diff --git a/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-zeebe-user-task.js b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-zeebe-user-task.js
new file mode 100644
index 0000000..f0758e2
--- /dev/null
+++ b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-zeebe-user-task.js
@@ -0,0 +1,22 @@
+export const template = {
+  'name': 'Zeebe User Task Hidden Property',
+  'id': 'com.camunda.example.ZeebeUserTaskHiddenProperty',
+  'description': 'A template to define a value less hidden property for a Zeebe user task.',
+  'version': 1,
+  'appliesTo': [
+    'bpmn:Task'
+  ],
+  'elementType': {
+    'value': 'bpmn:UserTask'
+  },
+  'properties': [
+    {
+      'type': 'Hidden',
+      'binding': {
+        'type': 'zeebe:userTask',
+      }
+    }
+  ]
+};
+
+export const errors = null;
\ No newline at end of file
diff --git a/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js b/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
index cf01da4..50fa63a 100644
--- a/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
+++ b/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
@@ -199,6 +199,12 @@ describe('validation', function() {
     it('element-type-invalid');
 
 
+    it('hidden-property');
+
+
+    it('hidden-zeebe-user-task');
+
+
     describe('element type - event definition', function() {
 
       it('element-type-event-definition');

From 9238f24a6cafa08b445981d959e8d7ca3a85f498 Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Thu, 14 Aug 2025 16:58:01 +0200
Subject: [PATCH 3/6] test: added a new test setup to verify for warnings

- less strict warnings
---
 .../test/helpers/index.js                     | 93 ++++++++++++++++++-
 .../src/defs/properties.json                  |  2 +-
 .../test/fixtures/hidden-property.js          |  8 ++
 .../test/spec/validationSpec.js               | 22 ++++-
 4 files changed, 116 insertions(+), 9 deletions(-)

diff --git a/packages/element-templates-json-schema-shared/test/helpers/index.js b/packages/element-templates-json-schema-shared/test/helpers/index.js
index cf5ea81..996059a 100644
--- a/packages/element-templates-json-schema-shared/test/helpers/index.js
+++ b/packages/element-templates-json-schema-shared/test/helpers/index.js
@@ -10,11 +10,13 @@ const AjvErrors = require('ajv-errors');
 
 module.exports = {
   createValidator,
-  withErrorMessages
+  withErrorMessages,
+  withDeprecationWarnings
 };
 
-function createValidator(schema, errors) {
+function createValidator(schema, errors, deprecations) {
 
+  let deprecationWarnings = [];
   const ajv = new Ajv({
     allErrors: true,
     strict: false,
@@ -23,7 +25,60 @@ function createValidator(schema, errors) {
 
   AjvErrors(ajv);
 
-  return ajv.compile(withErrorMessages(schema, errors));
+  ajv.addKeyword({
+    keyword: 'isDeprecated',
+    errors: true,
+    compile(schema, parentSchema) {
+      return function(data, dataCtx) {
+        if (schema) {
+          deprecationWarnings = [];
+
+          // AJV doesn't support real warnings, so this adds a non-strict validation with keyword 'isDeprecated'
+          const deprecationWarning = {
+            keyword: 'isDeprecated',
+
+            // TODO: schemaPath
+            dataPath: dataCtx.dataPath,
+            message: parentSchema.deprecatedWarning || 'This property is deprecated',
+          };
+
+          deprecationWarnings.push({
+            id: dataCtx.rootData.id,
+            warningDescription: deprecationWarning,
+          });
+
+          // just return true to not fail validation
+          return true;
+        }
+        return true;
+      };
+    }
+  });
+
+  const validator = ajv.compile(withErrorMessages(withDeprecationWarnings(schema, deprecations), errors));
+
+
+  const getDeprecationWarnings = function(data) {
+    if (deprecationWarnings.length > 0 && data.id === deprecationWarnings[0].id) {
+      return deprecationWarnings.map(warning => warning.warningDescription);
+    }
+  };
+
+  // wrapper function checks for warnings before each validation
+  const wrappedValidator = function(data, ...args) {
+
+    // Empty deprecation before each validation
+    deprecationWarnings = [];
+
+    const result = validator.call(this, data, ...args);
+
+    wrappedValidator.errors = validator.errors;
+    wrappedValidator.warnings = getDeprecationWarnings(data);
+
+    return result;
+  };
+
+  return wrappedValidator;
 }
 
 function withErrorMessages(schema, errors) {
@@ -71,4 +126,34 @@ function eqlErrors(chai, utils) {
   });
 }
 
-chai.use(eqlErrors);
\ No newline at end of file
+chai.use(eqlErrors);
+
+function withDeprecationWarnings(schema, deprecations) {
+  if (!deprecations || !deprecations.length) {
+    return schema;
+  }
+
+  // clone a new copy
+  let newSchema = JSON.parse(JSON.stringify(schema));
+
+  // set deprecation warnings for given paths
+  forEach(deprecations, function(deprecation) {
+    newSchema = setDeprecationWarning(newSchema, deprecation);
+  });
+
+  return newSchema;
+}
+
+function setDeprecationWarning(schema, deprecation) {
+  const {
+    path,
+    warningMessage
+  } = deprecation;
+
+  const deprecationPath = [
+    ...path,
+    'deprecatedWarning'
+  ];
+
+  return set(schema, deprecationPath, warningMessage);
+}
\ No newline at end of file
diff --git a/packages/zeebe-element-templates-json-schema/src/defs/properties.json b/packages/zeebe-element-templates-json-schema/src/defs/properties.json
index 704b386..0721503 100644
--- a/packages/zeebe-element-templates-json-schema/src/defs/properties.json
+++ b/packages/zeebe-element-templates-json-schema/src/defs/properties.json
@@ -662,7 +662,7 @@
                   { "required": [ "generatedValue" ] }
                 ]
               },
-              "deprecated": true
+              "isDeprecated": true
             }
           ]
         }
diff --git a/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
index 1ba89ba..fecbbc6 100644
--- a/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
+++ b/packages/zeebe-element-templates-json-schema/test/fixtures/hidden-property.js
@@ -27,3 +27,11 @@ export const template = {
 };
 
 export const errors = null;
+
+export const warnings = [
+  {
+    keyword: 'isDeprecated',
+    dataPath: '/properties/1',
+    message: 'Hidden property must specify either "value" or "generatedValue"'
+  }
+];
\ No newline at end of file
diff --git a/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js b/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
index 50fa63a..56254c2 100644
--- a/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
+++ b/packages/zeebe-element-templates-json-schema/test/spec/validationSpec.js
@@ -5,12 +5,13 @@ const util = require('util');
 const schema = require('../../resources/schema.json');
 
 const errorMessages = require('../../resources/error-messages.json');
+const deprecatedWarnings = require('../../resources/deprecated-warnings.json');
 
 const {
   createValidator
 } = require('../../../element-templates-json-schema-shared/test/helpers');
 
-const validator = createValidator(schema, errorMessages);
+const validator = createValidator(schema, errorMessages, deprecatedWarnings);
 
 // we save this for some other shinanigans
 const iit = it;
@@ -20,10 +21,12 @@ function validateTemplate(template) {
   const valid = validator(template);
 
   const errors = validator.errors;
+  const warnings = validator.warnings;
 
   return {
     valid,
-    errors
+    errors,
+    warnings
   };
 }
 
@@ -40,16 +43,27 @@ function createTest(name, file, it) {
 
     const {
       errors: expectedErrors,
-      template
+      template,
+      warnings: expectedWarnings
     } = testDefinition;
 
     // when
     const {
-      errors
+      errors,
+      warnings
     } = validateTemplate(template);
 
     // then
     expect(errors).to.eqlErrors(expectedErrors);
+
+    // less strict check for warnings
+    if (expectedWarnings) {
+      expect(warnings).to.eql(expectedWarnings);
+    } else if (warnings && warnings.length > 0) {
+
+      // log warnings without failing the test
+      warnings.forEach(x => console.warn('Deprecation warning:', x.message));
+    }
   });
 }
 

From e84f1d692df8cd52b343da8c90f6901f86fe6f20 Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Thu, 14 Aug 2025 16:59:28 +0200
Subject: [PATCH 4/6] test(warnings): added expected warnings

- added deprecated-warnings task
---
 .../package.json                              |  3 +-
 .../src/deprecated-warnings.json              | 17 +++++++
 tasks/generate-deprecated-warnings.js         | 49 +++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
 create mode 100644 tasks/generate-deprecated-warnings.js

diff --git a/packages/zeebe-element-templates-json-schema/package.json b/packages/zeebe-element-templates-json-schema/package.json
index 1c9fce5..fbc12cb 100644
--- a/packages/zeebe-element-templates-json-schema/package.json
+++ b/packages/zeebe-element-templates-json-schema/package.json
@@ -10,8 +10,9 @@
     "test:integration": "mocha --reporter=spec --recursive test/integration",
     "dev": "npm run test -- --watch",
     "all": "run-s build test",
-    "build": "run-s build:error-messages build:schema",
+    "build": "run-s build:error-messages build:deprecated-warnings build:schema",
     "build:error-messages": "node ../../tasks/generate-error-messages.js --input=./src/error-messages.json --output=./resources/error-messages.json",
+    "build:deprecated-warnings": "node ../../tasks/generate-deprecated-warnings.js --input=./src/deprecated-warnings.json --output=./resources/deprecated-warnings.json",
     "build:schema": "node ../../tasks/generate-schema.js --input=./src/schema.json --output=./resources/schema.json",
     "prepare": "run-s build"
   },
diff --git a/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json b/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
new file mode 100644
index 0000000..8106864
--- /dev/null
+++ b/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
@@ -0,0 +1,17 @@
+[  
+    {
+  "path": [
+    "definitions",
+    "properties",
+    "allOf",
+    1,
+    "items",
+    "allOf",
+    23,
+    "then",
+    "anyOf",
+    2
+    ],
+  "warningMessage": "Hidden property must specify either \"value\" or \"generatedValue\""
+  }
+]
\ No newline at end of file
diff --git a/tasks/generate-deprecated-warnings.js b/tasks/generate-deprecated-warnings.js
new file mode 100644
index 0000000..32eacf7
--- /dev/null
+++ b/tasks/generate-deprecated-warnings.js
@@ -0,0 +1,49 @@
+const readFile = require('fs').readFileSync,
+      writeFile = require('fs').writeFileSync,
+      mkdir = require('fs').mkdirSync;
+
+const pathJoin = require('path').join,
+      dirname = require('path').dirname;
+
+const mri = require('mri');
+
+const argv = process.argv.slice(2);
+
+async function bundleWarnings(warningMessages, path) {
+  return writeWarnings(warningMessages, path);
+}
+
+
+function writeWarnings(warningMessages, path) {
+  const filePath = pathJoin(path);
+
+  try {
+    mkdir(dirname(filePath));
+  } catch {
+
+    // directory may already exist
+  }
+
+  writeFile(filePath, JSON.stringify(warningMessages, 0, 2));
+
+  return filePath;
+}
+
+
+const {
+  input,
+  output
+} = mri(argv, {
+  alias: {
+    i: 'input',
+    o: 'output'
+  }
+});
+
+if (!input || !output) {
+  console.error('Arguments missing.');
+  console.error('Example: node tasks/generate-error-messages.js --input=./src/error-messages.json --output=./resources/error-messages.json');
+  process.exit(1);
+}
+
+bundleWarnings(JSON.parse(readFile(input)), output);

From ff0237f7a172fffa4a68b76c7d81d38ce3ed81db Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Thu, 14 Aug 2025 17:21:38 +0200
Subject: [PATCH 5/6] chore: cleanup

---
 .../test/helpers/index.js                     | 99 +------------------
 .../test/helpers/utils.js                     | 97 ++++++++++++++++++
 2 files changed, 101 insertions(+), 95 deletions(-)
 create mode 100644 packages/element-templates-json-schema-shared/test/helpers/utils.js

diff --git a/packages/element-templates-json-schema-shared/test/helpers/index.js b/packages/element-templates-json-schema-shared/test/helpers/index.js
index 996059a..910a80c 100644
--- a/packages/element-templates-json-schema-shared/test/helpers/index.js
+++ b/packages/element-templates-json-schema-shared/test/helpers/index.js
@@ -1,17 +1,10 @@
-const {
-  forEach,
-  set
-} = require('min-dash');
-
-const chai = require('chai');
-
 const { default: Ajv } = require('ajv');
 const AjvErrors = require('ajv-errors');
 
+const { withErrorMessages, withDeprecationWarnings, getDeprecationWarnings } = require('./utils');
+
 module.exports = {
-  createValidator,
-  withErrorMessages,
-  withDeprecationWarnings
+  createValidator
 };
 
 function createValidator(schema, errors, deprecations) {
@@ -57,13 +50,6 @@ function createValidator(schema, errors, deprecations) {
 
   const validator = ajv.compile(withErrorMessages(withDeprecationWarnings(schema, deprecations), errors));
 
-
-  const getDeprecationWarnings = function(data) {
-    if (deprecationWarnings.length > 0 && data.id === deprecationWarnings[0].id) {
-      return deprecationWarnings.map(warning => warning.warningDescription);
-    }
-  };
-
   // wrapper function checks for warnings before each validation
   const wrappedValidator = function(data, ...args) {
 
@@ -73,87 +59,10 @@ function createValidator(schema, errors, deprecations) {
     const result = validator.call(this, data, ...args);
 
     wrappedValidator.errors = validator.errors;
-    wrappedValidator.warnings = getDeprecationWarnings(data);
+    wrappedValidator.warnings = getDeprecationWarnings(deprecationWarnings, data);
 
     return result;
   };
 
   return wrappedValidator;
-}
-
-function withErrorMessages(schema, errors) {
-
-  if (!errors || !errors.length) {
-    return schema;
-  }
-
-  // clone a new copy
-  let newSchema = JSON.parse(JSON.stringify(schema));
-
-  // set <errorMessage> keyword for given path
-  forEach(errors, function(error) {
-    newSchema = setErrorMessage(newSchema, error);
-  });
-
-  return newSchema;
-}
-
-function setErrorMessage(schema, error) {
-  const {
-    path,
-    errorMessage
-  } = error;
-
-  const errorMessagePath = [
-    ...path,
-    'errorMessage'
-  ];
-
-  return set(schema, errorMessagePath, errorMessage);
-}
-
-function eqlErrors(chai, utils) {
-
-  const Assertion = chai.Assertion;
-
-  Assertion.addMethod('eqlErrors', function(expectedErrors, filter) {
-
-    const actualErrors = this._obj;
-
-    // formats the validation errors, so that they can be used directly in the fixture files.
-    this.eql(expectedErrors,
-      `Errors from validation do not match expected.\n\tValidation returned this error (you can use it in the fixture):\n\t${JSON.stringify(actualErrors, null, 2).replace(/"([^"]+)":/g, '$1:')}\n`);
-  });
-}
-
-chai.use(eqlErrors);
-
-function withDeprecationWarnings(schema, deprecations) {
-  if (!deprecations || !deprecations.length) {
-    return schema;
-  }
-
-  // clone a new copy
-  let newSchema = JSON.parse(JSON.stringify(schema));
-
-  // set deprecation warnings for given paths
-  forEach(deprecations, function(deprecation) {
-    newSchema = setDeprecationWarning(newSchema, deprecation);
-  });
-
-  return newSchema;
-}
-
-function setDeprecationWarning(schema, deprecation) {
-  const {
-    path,
-    warningMessage
-  } = deprecation;
-
-  const deprecationPath = [
-    ...path,
-    'deprecatedWarning'
-  ];
-
-  return set(schema, deprecationPath, warningMessage);
 }
\ No newline at end of file
diff --git a/packages/element-templates-json-schema-shared/test/helpers/utils.js b/packages/element-templates-json-schema-shared/test/helpers/utils.js
new file mode 100644
index 0000000..83704bc
--- /dev/null
+++ b/packages/element-templates-json-schema-shared/test/helpers/utils.js
@@ -0,0 +1,97 @@
+const chai = require('chai');
+
+const {
+  forEach,
+  set
+} = require('min-dash');
+
+function withErrorMessages(schema, errors) {
+
+  if (!errors || !errors.length) {
+    return schema;
+  }
+
+  // clone a new copy
+  let newSchema = JSON.parse(JSON.stringify(schema));
+
+  // set <errorMessage> keyword for given path
+  forEach(errors, function(error) {
+    newSchema = setErrorMessage(newSchema, error);
+  });
+
+  return newSchema;
+}
+
+function setErrorMessage(schema, error) {
+  const {
+    path,
+    errorMessage
+  } = error;
+
+  const errorMessagePath = [
+    ...path,
+    'errorMessage'
+  ];
+
+  return set(schema, errorMessagePath, errorMessage);
+}
+
+
+function withDeprecationWarnings(schema, deprecations) {
+  if (!deprecations || !deprecations.length) {
+    return schema;
+  }
+
+  // clone a new copy
+  let newSchema = JSON.parse(JSON.stringify(schema));
+
+  // set deprecation warnings for given paths
+  forEach(deprecations, function(deprecation) {
+    newSchema = setDeprecationWarning(newSchema, deprecation);
+  });
+
+  return newSchema;
+}
+
+function setDeprecationWarning(schema, deprecation) {
+  const {
+    path,
+    warningMessage
+  } = deprecation;
+
+  const deprecationPath = [
+    ...path,
+    'deprecatedWarning'
+  ];
+
+  return set(schema, deprecationPath, warningMessage);
+}
+
+function getDeprecationWarnings(deprecationWarnings, data) {
+  if (deprecationWarnings.length > 0 && data.id === deprecationWarnings[0].id) {
+    return deprecationWarnings.map(warning => warning.warningDescription);
+  }
+};
+
+function eqlErrors(chai, utils) {
+
+  const Assertion = chai.Assertion;
+
+  Assertion.addMethod('eqlErrors', function(expectedErrors, filter) {
+
+    const actualErrors = this._obj;
+
+    // formats the validation errors, so that they can be used directly in the fixture files.
+    this.eql(expectedErrors,
+      `Errors from validation do not match expected.\n\tValidation returned this error (you can use it in the fixture):\n\t${JSON.stringify(actualErrors, null, 2).replace(/"([^"]+)":/g, '$1:')}\n`);
+  });
+}
+
+chai.use(eqlErrors);
+
+module.exports = {
+  withErrorMessages,
+  withDeprecationWarnings,
+  getDeprecationWarnings
+};
+

From bbf8065c7d046cb335a313488dda75516a7f86c9 Mon Sep 17 00:00:00 2001
From: Abdul Ahad <abdul.ahad@camunda.com>
Date: Tue, 19 Aug 2025 17:10:17 +0200
Subject: [PATCH 6/6] chore: rebase adjusted

---
 .../src/deprecated-warnings.json                                | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json b/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
index 8106864..4743ec0 100644
--- a/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
+++ b/packages/zeebe-element-templates-json-schema/src/deprecated-warnings.json
@@ -7,7 +7,7 @@
     1,
     "items",
     "allOf",
-    23,
+    25,
     "then",
     "anyOf",
     2