public void createExternalReference(String fromAddress, String libraryName,
			String externalLabel, int opIndex) throws Exception {
		createExternalReference(fromAddress, libraryName, externalLabel, null, opIndex,
			RefType.DATA, SourceType.IMPORTED);
	}
Creates a sting data type instance at the specified address, repeated {@code N} times.

@param addressString address.
@param dt {@link AbstractStringDataType} string type to place at address.
@param n repeat count.
Ghidra/Features/Base/src/main/java/ghidra/program/database/ProgramBuilder.java