using VariablePrepare.prepare won't prepare all variables correctly

[azin97]

Hi,
I have an issue with replacing variables in docx file. The file contains a lot of variables and is formatted. Most of them are replaced correctly but some aren't. Here's code example:

  public byte [] replaceVariables(Map<String, String> placeholderMap, byte[] bytes) throws Exception {
    WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.load(new ByteArrayInputStream(bytes));
    VariablePrepare.prepare(wordMLPackage);
    MainDocumentPart mainDocumentPart = wordMLPackage.getMainDocumentPart();
    mainDocumentPart.variableReplace(placeholderMap);

    ByteArrayOutputStream baos= new ByteArrayOutputStream();
    wordMLPackage.save(baos);

    return baos.toByteArray();
  }

		<w:p w14:paraId="2EFE45B1" w14:textId="42A5B701" w:rsidR="008355AE" w:rsidRDefault="00B46D75" w:rsidP="00952A23">
			<w:pPr>
				<w:pStyle w:val="Header3"/>
				<w:spacing w:after="19"/>
				<w:ind w:left="10" w:right="709"/>
			</w:pPr>
			<w:r>
				<w:t xml:space="preserve">FIRST NAME       </w:t>
			</w:r>
			<w:r w:rsidR="005D53E9" w:rsidRPr="00637C75">
				<w:rPr>
					<w:color w:val="FF0000"/>
					<w:sz w:val="20"/>
					<w:szCs w:val="20"/>
				</w:rPr>
				<w:t>${</w:t>
			</w:r>
			<w:proofErr w:type="spellStart"/>
			<w:r w:rsidR="005D53E9" w:rsidRPr="00637C75">
				<w:rPr>
					<w:color w:val="FF0000"/>
					<w:sz w:val="20"/>
					<w:szCs w:val="20"/>
				</w:rPr>
				<w:t>first_</w:t>
			</w:r>
			<w:r w:rsidR="005D53E9" w:rsidRPr="00637C75">
				<w:rPr>
					<w:color w:val="FF0000"/>
				</w:rPr>
				<w:t>name</w:t>
			</w:r>
			<w:proofErr w:type="spellEnd"/>
			<w:r w:rsidR="005D53E9" w:rsidRPr="00637C75">
				<w:rPr>
					<w:color w:val="FF0000"/>
				</w:rPr>
				<w:t>}</w:t>
			</w:r>
		</w:p>

In logs i got:
org.docx4j.XmlUtils: Invalid key 'first</w:t></w:r><w:r><w:rPr><w:color w:val="FF0000"/></w:rPr><w:t>name' or key not mapped to a value

Example of placeholder which is replaced by variable correctly:
${last_name}
Example result:
Smith
Example of placeholder which is not replaced by variable correctly:
FIRST NAME ${first_name}
Example result:
first_name

When i manually clear formatting on the placeholder field in docx file it works correctly, but is there any other way for preparing all variables correctly?