Kafka connect transformation "Error getting config definition from Transformation"

Question

I have a kafka connector with custom transformer plugin added and it complians as:

Error getting config definition from Transformation

Here's my connector config:

apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: "${connector_name}-s3-sink-connector"
  namespace: ${namespace}
  labels:
    strimzi.io/cluster: "${connect_cluster_name}"
spec:
  autoRestart:
    enabled: true
  class: io.confluent.connect.s3.S3SinkConnector
  tasksMax: ${num_tasks}
  config:
     "consumer.auto.offset.reset": "none"
     "flush.size": "5000"
     "format.class": "io.confluent.connect.s3.format.json.JsonFormat"
     "key.converter": "org.apache.kafka.connect.storage.StringConverter"
     "locale": "de_DE"
     "name": "${connector_name}-s3-sink-connector"
     "partition.duration.ms": "3600000"
     "partitioner.class": "io.confluent.connect.storage.partitioner.TimeBasedPartitioner"
     "path.format": "'partition_date'=YYYY-MM-dd/'hour'=HH"
     "rotate.interval.ms": "${rotate_interval_ms}"
     "s3.bucket.name": "${bucket_name}"
     "s3.compression.type": "gzip"
     "s3.region": "eu-central-1"
     "s3.compression.level": 1
     "s3.part.size": "5242880"
     "schemas.enable": "false"
     "storage.class": "io.confluent.connect.s3.storage.S3Storage"
     "timezone": "UTC"
     "topics": "events_v2"
     "topics.dir": "public/raw"
     "timestamp.extractor" : "me.mine.kafka.connect.storage.partitioner.HeaderFieldTimestampExtractor"
     "value.converter": "org.apache.kafka.connect.json.JsonConverter"
     "value.converter.schemas.enable": "false"
     "transforms" : "offerListExtractHeaderTransformer"
     "transforms.offerListExtractHeaderTransformer.header.key.eventCreationTime" : "offerListEventTime"
     "transforms.offerListExtractHeaderTransformer.type" : "me.mine.kafka.connect.transforms.ExtractHeaderTransformer$Value"
     "errors.tolerance": "none"
     "errors.logs.enable": "true"
     "errors.log.include.messages": "true"

I have tried adding backslash(\) to escape $ but that also says "invalid escape character".

Any ideas what could be wrong