@Override
    public String getField(int rowNum, String fieldName) {
        String fieldValue = "";
        try {
            if (isContextField(fieldName)) {
                return getContextField(fieldName);
            }
            if (StringUtils.startsWith(fieldName, ROOT_KEY)) {
                fieldValue = this.getRootField(fieldName);
            } else if (StringUtils.startsWith(fieldName, CHILD_KEY)) {
                if (childRoot != null && rowNum < childRoot.size()) {
                    fieldValue = this.getChildField(rowNum, fieldName);
                }
            }
            return fieldValue;
        } catch (Exception e) {
            LOG.error(e.getMessage(), e);
        }
        return fieldValue;
    }
getField
@param rowNum
@param fieldName
@return
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/decode/PbSourceData.java