{"record":{"id":"de9396f1c8d47bdd","repo":"apache/flink","slug":"fieldset-to-add-must-not-be-null-de9396","errorCode":null,"errorMessage":"FieldSet to add must not be null.","messagePattern":"FieldSet to add must not be null\\.","errorType":"validation","errorClass":"IllegalArgumentException","httpStatus":null,"severity":"error","filePath":"flink-core/src/main/java/org/apache/flink/api/common/operators/util/FieldSet.java","lineNumber":156,"sourceCode":"        }\n    }\n\n    // --------------------------------------------------------------------------------------------\n\n    public FieldSet addField(Integer fieldID) {\n        if (fieldID == null) {\n            throw new IllegalArgumentException(\"Field ID must not be null.\");\n        }\n        return new FieldSet(this, fieldID);\n    }\n\n    public FieldSet addFields(int... fieldIDs) {\n        return new FieldSet(this, fieldIDs);\n    }\n\n    public FieldSet addFields(FieldSet set) {\n        if (set == null) {\n            throw new IllegalArgumentException(\"FieldSet to add must not be null.\");\n        }\n\n        if (set.size() == 0) {\n            return this;\n        } else if (this.size() == 0) {\n            return set;\n        } else {\n            return new FieldSet(this, set);\n        }\n    }\n\n    public boolean contains(Integer columnIndex) {\n        return this.collection.contains(columnIndex);\n    }\n\n    public int size() {\n        return this.collection.size();\n    }","sourceCodeStart":138,"sourceCodeEnd":174,"githubUrl":"https://github.com/apache/flink/blob/2f3c205e9266cb30240eb7f4fdab15cad629a70f/flink-core/src/main/java/org/apache/flink/api/common/operators/util/FieldSet.java#L138-L174","documentation":"Error \"FieldSet to add must not be null.\" thrown in apache/flink.","triggerScenarios":"Triggered at runtime when the operation fails because: FieldSet to add must not be null.","commonSituations":"Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: FieldSet to add must not be null.","solutions":["Address the cause reported by the error message: FieldSet to add must not be null.","Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry."],"exampleFix":"Correct the condition described (\"FieldSet to add must not be null.\") and rerun the job or command.","handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"2f3c205e9266cb30240eb7f4fdab15cad629a70f","analyzedAt":"2026-08-14T08:48:24.518Z","schemaVersion":2},"datasetVersion":"2026-08-14T10:17:34.591Z"}