Issue #7067 : Kafka Consumer step fails when run inside async web service

core/src/main/java/org/apache/hop/core/variables/Variables.java

@@ -65,6 +65,9 @@ public void copyFrom(IVariables variables) {
       // the same object as the argument.
       String[] variableNames = variables.getVariableNames();
       for (String variableName : variableNames) {
+        if (Utils.isEmpty(variableName)) {
+          continue;
+        }
         properties.put(variableName, variables.getVariable(variableName));
       }
     }
@@ -140,6 +143,11 @@ public String[] getVariableNames() {
 
   @Override
   public synchronized void setVariable(String variableName, String variableValue) {
+    // Reject null/empty names: HashMap allows null keys, but callers that iterate
+    // names and check Immutable Sets (Set.of) throw NPE on contains(null) — issue #7067.
+    if (Utils.isEmpty(variableName)) {
+      return;
+    }
     if (variableValue != null) {
       properties.put(variableName, variableValue);
     } else {

core/src/test/java/org/apache/hop/core/variables/VariablesTest.java

@@ -153,4 +153,23 @@ void testEnvironmentSubstitute() {
         new String[] {"DataOne", "TheDataOne"},
         vars.resolve(new String[] {"${VarOne}", "The${VarOne}"}));
   }
+
+  /**
+   * Null or empty variable names must not enter the properties map (issue #7067). A null key caused
+   * NPE later when checking Const.INTERNAL_*_VARIABLES Set.of collections.
+   */
+  @Test
+  void setVariableIgnoresNullAndEmptyNames() {
+    Variables vars = new Variables();
+    vars.setVariable(null, "shouldNotStore");
+    vars.setVariable("", "shouldNotStore");
+    vars.setVariable("valid", "ok");
+
+    for (String name : vars.getVariableNames()) {
+      assertTrue(name != null && !name.isEmpty());
+    }
+    assertEquals("ok", vars.getVariable("valid"));
+    assertNull(vars.getVariable(null));
+    assertNull(vars.getVariable(""));
+  }
 }

engine/src/main/java/org/apache/hop/pipeline/TransformWithMappingMeta.java

@@ -313,6 +313,10 @@ public static void addMissingVariables(IVariables fromSpace, IVariables toSpace)
     }
     String[] variableNames = toSpace.getVariableNames();
     for (String variable : variableNames) {
+      // Skip null/empty names: Set.contains(null) throws NPE and empty keys are invalid
+      if (Utils.isEmpty(variable)) {
+        continue;
+      }
       if (fromSpace.getVariable(variable) == null) {
         fromSpace.setVariable(variable, toSpace.getVariable(variable));
       }
@@ -326,6 +330,10 @@ public static void replaceVariableValues(
     }
     String[] variableNames = replaceBy.getVariableNames();
     for (String variableName : variableNames) {
+      // Skip null/empty names: Immutable Set.contains(null) throws NPE (issue #7067)
+      if (Utils.isEmpty(variableName)) {
+        continue;
+      }
       if (childPipelineMeta.getVariable(variableName) != null
           && !isInternalVariable(variableName, type)) {
         childPipelineMeta.setVariable(variableName, replaceBy.getVariable(variableName));
@@ -347,10 +355,10 @@ private static boolean isInternalVariable(String variableName, String type) {
   }
 
   private static boolean isPipelineInternalVariable(String variableName) {
-    return Const.INTERNAL_PIPELINE_VARIABLES.contains(variableName);
+    return variableName != null && Const.INTERNAL_PIPELINE_VARIABLES.contains(variableName);
   }
 
   private static boolean isWorkflowInternalVariable(String variableName) {
-    return Const.INTERNAL_WORKFLOW_VARIABLES.contains(variableName);
+    return variableName != null && Const.INTERNAL_WORKFLOW_VARIABLES.contains(variableName);
   }
 }

engine/src/test/java/org/apache/hop/pipeline/TransformWithMappingMetaTest.java

@@ -16,7 +16,11 @@
  */
 package org.apache.hop.pipeline;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 import org.apache.hop.core.Const;
 import org.apache.hop.core.HopEnvironment;
@@ -168,4 +172,39 @@ void replaceVariablesWithPipelineInternalVariablesTest() {
     // keep child only variables
     assertEquals(variableChildOnly, childVariables.getVariable(variableChildOnly));
   }
+
+  /**
+   * Reproduces issue #7067: a null variable name in the parent space used to NPE when checking
+   * internal variable sets (Set.of(...).contains(null)). Async web services could inject a null key
+   * when header content variable was unset.
+   */
+  @Test
+  void replaceVariableValuesSkipsNullVariableNames() {
+    String variableOverwrite = "paramOverwrite";
+    IVariables childVariables = new Variables();
+    childVariables.setVariable(variableOverwrite, "childValue");
+
+    IVariables replaceByParentVariables = mock(IVariables.class);
+    when(replaceByParentVariables.getVariableNames())
+        .thenReturn(new String[] {null, "", variableOverwrite});
+    when(replaceByParentVariables.getVariable(variableOverwrite)).thenReturn("parentValue");
+
+    assertDoesNotThrow(
+        () ->
+            TransformWithMappingMeta.replaceVariableValues(
+                childVariables, replaceByParentVariables));
+    assertEquals("parentValue", childVariables.getVariable(variableOverwrite));
+  }
+
+  @Test
+  void addMissingVariablesSkipsNullVariableNames() {
+    IVariables fromSpace = new Variables();
+    IVariables toSpace = mock(IVariables.class);
+    when(toSpace.getVariableNames()).thenReturn(new String[] {null, "", "addedVar"});
+    when(toSpace.getVariable("addedVar")).thenReturn("addedValue");
+
+    assertDoesNotThrow(() -> TransformWithMappingMeta.addMissingVariables(fromSpace, toSpace));
+    assertEquals("addedValue", fromSpace.getVariable("addedVar"));
+    assertNull(fromSpace.getVariable(null));
+  }
 }

plugins/misc/async/src/main/java/org/apache/hop/www/async/AsyncRunServlet.java

@@ -171,11 +171,13 @@ public void doGet(HttpServletRequest request, HttpServletResponse response) {
       workflow.initializeFrom(variables);
       workflow.setVariable("SERVER_OBJECT_ID", serverObjectId);
 
-      // See if we need to pass a variable with the content in it...
-      //
-      // Read the content posted?
+      // Pass body and header content into variables when configured.
+      // Guard both independently so an unset header variable never injects a null key
+      // (which caused NPE in Kafka Consumer init via replaceVariableValues — issue #7067).
       //
       String contentVariable = variables.resolve(webService.getBodyContentVariable());
+      String headerContentVariable = variables.resolve(webService.getHeaderContentVariable());
+
       String content = "";
       if (StringUtils.isNotEmpty(contentVariable)) {
         try (InputStream in = request.getInputStream()) {
@@ -193,24 +195,21 @@ public void doGet(HttpServletRequest request, HttpServletResponse response) {
           }
         }
         workflow.setVariable(contentVariable, Const.NVL(content, ""));
+      }
 
-        String headerContentVariable = variables.resolve(webService.getHeaderContentVariable());
-        String headerContent = "";
-        if (StringUtils.isNotEmpty(headerContentVariable)) {
-          // Create JSON object containing all request headers
-          ObjectMapper objectMapper = new ObjectMapper();
-          ObjectNode headersJson = objectMapper.createObjectNode();
-
-          Enumeration<String> headerNames = request.getHeaderNames();
-          while (headerNames.hasMoreElements()) {
-            String headerName = headerNames.nextElement();
-            String headerValue = request.getHeader(headerName);
-            headersJson.put(headerName, headerValue);
-          }
-          headerContent = objectMapper.writeValueAsString(headersJson);
-        }
+      if (StringUtils.isNotEmpty(headerContentVariable)) {
+        // Create JSON object containing all request headers
+        ObjectMapper objectMapper = new ObjectMapper();
+        ObjectNode headersJson = objectMapper.createObjectNode();
 
-        workflow.setVariable(headerContentVariable, headerContent);
+        Enumeration<String> headerNames = request.getHeaderNames();
+        while (headerNames.hasMoreElements()) {
+          String headerName = headerNames.nextElement();
+          String headerValue = request.getHeader(headerName);
+          headersJson.put(headerName, headerValue);
+        }
+        String headerContent = objectMapper.writeValueAsString(headersJson);
+        workflow.setVariable(headerContentVariable, Const.NVL(headerContent, ""));
       }
 
       // Set all the other parameters as variables/parameters...