public void addRegAndValueToFilter(String contextRegister, BigInteger value) {
		if (contextRegisters.contains(contextRegister)) {
			throw new IllegalStateException("Filter can have only one value per register!");
		}
		contextRegisters.add(contextRegister);
		values.put(contextRegister, value);
	}
Add a pair (register,value) to the filter.

@param contextRegister - the context register
@param value           - the value the filter allows
@throws IllegalStateException if you add a value for a register that already has a value in the filter
Ghidra/Features/BytePatterns/src/main/java/ghidra/bitpatterns/info/ContextRegisterFilter.java