public ModifyableTableDescriptor setReadOnly(final boolean readOnly) {
      return setValue(READONLY_KEY, Boolean.toString(readOnly));
    }
Setting the table as read only sets all the columns in the table as read only. By default all
tables are modifiable, but if the readOnly flag is set to true then the contents of the table
can only be read but not modified.
@param readOnly True if all of the columns in the table should be read only.
@return the modifyable TD
hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java