How to make the spring batch Itemreader return a list by reading from a file

Question

In Spring Batch does anyone know how to make Flatfileitemreaderbuilder return a list? Or if there is any other class that reads the file and returns a list?
I have this Reader code:

  fun readFilesWithFixedPosition(
        @Value("#{jobParameters['arquivoClientes']}")
        customerFile: Resource
    ): FlatFileItemReader<List<Cadpos>> {

        return FlatFileItemReaderBuilder<List<Cadpos>>()
            .name("readFilesWithFixedPosition")
            .resource(customerFile)
            .fixedLength()
            .columns(*columns)
            .names(*names)
            .strict(false)
            .targetType(getObjectType())
            .build()
    }

    fun getObjectType(): Class<List<Cadpos>> {
        val myList: List<Cadpos> = ArrayList()
        return myList.javaClass
    }

But when reading this error is returned:

Caused by: org.springframework.beans.NotWritablePropertyException: Invalid property 'telefone' of bean class [java.util.ArrayList]: Bean property 'telefone' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.BeanWrapperImpl.createNotWritablePropertyException(BeanWrapperImpl.java:243)
    at org.springframework.beans.AbstractNestablePropertyAccessor.processLocalProperty(AbstractNestablePropertyAccessor.java:432)
    at org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue(AbstractNestablePropertyAccessor.java:278)
    at org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue(AbstractNestablePropertyAccessor.java:266)
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:104)
    at org.springframework.validation.DataBinder.applyPropertyValues(DataBinder.java:851)
    at org.springframework.validation.DataBinder.doBind(DataBinder.java:747)
    at org.springframework.validation.DataBinder.bind(DataBinder.java:732)
    at org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper.mapFieldSet(BeanWrapperFieldSetMapper.java:199)
    at org.springframework.batch.item.file.mapping.DefaultLineMapper.mapLine(DefaultLineMapper.java:43)
    at org.springframework.batch.item.file.FlatFileItemReader.doRead(FlatFileItemReader.java:185)
    ... 57 common frames omitted

As if after I converted to return a list I could no longer map the object. Does anyone have any idea how to fix?