Converts avro schema to big query schema, not a full fledged implementation, works with basic types, records, union and array

AvroToTableSchemaConverter.java

import com.google.api.services.bigquery.model.TableFieldSchema;
import com.google.api.services.bigquery.model.TableSchema;
import com.google.common.collect.ImmutableMap;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Type;

import java.util.ArrayList;
import java.util.List;

import static org.apache.avro.Schema.Type.*;

public class AvroToTableSchemaConverter {

    private AvroToTableSchemaConverter() {
    }

    public static TableSchema convert(Schema schema) {
        var ts = new TableSchema();
        var fields = generateTableFieldSchemas(schema);
        ts.setFields(fields);
        return ts;
    }

    private static List<TableFieldSchema> generateTableFieldSchemas(Schema schema) {
        var tableFieldSchemas = new ArrayList<TableFieldSchema>();
        if (schema != null) {
            for (Schema.Field field : schema.getFields()) {
                var tableFieldSchema =
                        new TableFieldSchema()
                                .setName(field.name())
                                .setMode("REQUIRED");

                var fieldSchema = field.schema();

                if (fieldSchema.getType() == UNION && fieldSchema.getTypes().get(0).getType() == NULL) {
                    tableFieldSchema
                            .setMode("NULLABLE");
                    fieldSchema = fieldSchema.getTypes().get(1);
                }

                if (fieldSchema.getType() == ARRAY) {
                    tableFieldSchema
                            .setMode("REPEATED");
                    fieldSchema = fieldSchema.getElementType();
                }

                if (fieldSchema.getType() == RECORD) {
                    tableFieldSchema
                            .setType("STRUCT")
                            .setFields(generateTableFieldSchemas(fieldSchema));
                } else {
                    tableFieldSchema
                            .setType(getBqType(fieldSchema));
                }

                tableFieldSchemas.add(tableFieldSchema);
            }
        }
        return tableFieldSchemas;
    }

    private static String getBqType(Schema schema) {
        var logicalType = getLogicalType(schema);

        if (schema.getType() == LONG && "timestamp-millis".equals(logicalType)) {
            return "TIMESTAMP";
        } else if (schema.getType() == INT && "date".equals(logicalType)) {
            return "DATE";
        } else {
            return AVRO_TYPES_TO_BIG_QUERY.get(schema.getType());
        }
    }

    private static String getLogicalType(Schema schema) {
        String logicalType = null;
        if (schema.getLogicalType() != null) {
            logicalType = schema.getLogicalType().getName();
        }
        return logicalType;
    }

    private static final ImmutableMap<Type, String> AVRO_TYPES_TO_BIG_QUERY = ImmutableMap.<Type, String>builder()
            .put(STRING, "STRING")
            .put(INT, "INTEGER")
            .put(DOUBLE, "FLOAT64")
            .put(BYTES, "NUMERIC")
            .put(BOOLEAN, "BOOL")
            .put(LONG, "INT64")
            .build();
}