code: public static RowTypeInfo projectFields(RowTypeInfo rowType, int[] fieldMapping) {
  		TypeInformation[] fieldTypes = new TypeInformation[fieldMapping.length];
  		String[] fieldNames = new String[fieldMapping.length];
  		for (int i = 0; i < fieldMapping.length; i++) {
  			fieldTypes[i] = rowType.getTypeAt(fieldMapping[i]);
  			fieldNames[i] = rowType.getFieldNames()[fieldMapping[i]];
  		}
  		return new RowTypeInfo(fieldTypes, fieldNames);
  	}
docs: Creates a {@link RowTypeInfo} with projected fields.
  
  @param rowType The original RowTypeInfo whose fields are projected
  @param fieldMapping The field mapping of the projection
  @return A RowTypeInfo with projected fields.