code: public _Private_IonManagedBinaryWriterBuilder withFlatImports(final SymbolTable... tables)
      {
          if (tables != null)
          {
              return withFlatImports(Arrays.asList(tables));
          }
          return this;
      }
docs: Adds imports, flattening them to make lookup more efficient.  This is particularly useful
  when a builder instance is long lived.