with ExternalTransform.service(self._expansion_service) as service:
        response = service.Expand(request)
        if response.error:
>         raise RuntimeError(response.error)
E         RuntimeError: java.lang.IllegalArgumentException: Cannot find field maxConnections in schema Fields:
E         Field{name=driverClassName, description=, type=STRING NOT NULL, options={{}}}
E         Field{name=jdbcUrl, description=, type=STRING NOT NULL, options={{}}}
E         Field{name=username, description=, type=STRING NOT NULL, options={{}}}
E         Field{name=password, description=, type=STRING NOT NULL, options={{}}}
E         Field{name=connectionProperties, description=, type=STRING, options={{}}}
E         Field{name=connectionInitSqls, description=, type=ITERABLE, options={{}}}
E         Field{name=readQuery, description=, type=STRING, options={{}}}
E         Field{name=writeStatement, description=, type=STRING, options={{}}}
E         Field{name=fetchSize, description=, type=INT16, options={{}}}
E         Field{name=outputParallelization, description=, type=BOOLEAN, options={{}}}
E         Field{name=autosharding, description=, type=BOOLEAN, options={{}}}
E         Encoding positions:
E         {connectionProperties=4, autosharding=10, password=3, writeStatement=7, outputParallelization=9, fetchSize=8, driverClassName=0, jdbcUrl=1, connectionInitSqls=5, username=2, readQuery=6}
E         Options:{{}}UUID: 49358cda-6f26-4080-86fc-36fcc5d52b44
E         	at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument(Preconditions.java:440)
E         	at org.apache.beam.sdk.schemas.Schema.indexOf(Schema.java:1365)
E         	at org.apache.beam.sdk.values.Row.getInt32(Row.java:154)
E         	at org.apache.beam.sdk.io.jdbc.JdbcSchemaIOProvider$JdbcSchemaIO.getDataSourceConfiguration(JdbcSchemaIOProvider.java:178)
E         	at org.apache.beam.sdk.io.jdbc.JdbcSchemaIOProvider$JdbcSchemaIO$2.expand(JdbcSchemaIOProvider.java:144)
E         	at org.apache.beam.sdk.io.jdbc.JdbcSchemaIOProvider$JdbcSchemaIO$2.expand(JdbcSchemaIOProvider.java:139)