title: solr search in a "content" field does not work
body: <p>I have uploaded and extract document in solr 6.0.0 and I see that it is indexed using the following query:</p>
  
  <p><a href="http://localhost:8983/solr/techproducts/select?indent=on&amp;q=id:doc1&amp;wt=json" rel="nofollow">http://localhost:8983/solr/techproducts/select?indent=on&amp;q=id:doc1&amp;wt=json</a></p>
  
  <pre><code>{
    "responseHeader":{
      "status":0,
      "QTime":1,
      "params":{
        "q":"id:doc1",
        "indent":"on",
        "wt":"json"}},
    "response":{"numFound":1,"start":0,"docs":[
        {
          "links":["http://www.education.gov.yk.ca/"],
          "id":"doc1",
          "last_modified":"2008-06-04T22:47:36Z",
          "title":[" PDF Test Page"],
          "content_type":["application/pdf"],
          "author":"Yukon Canada Yukon Department of Education",
          "author_s":"Yukon Canada Yukon Department of Education",
          "content":[" \n \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  PDF Test Page \n \n    \n  \n \nPDF Test File \n \nCongratulations, your computer is equipped with a PDF (Portable Document Format) \nreader!  You should be able to view any of the PDF documents and forms available on \nour site.  PDF forms are indicated by these icons:   or  .   \n \nYukon Department of Education \nBox 2703 \nWhitehorse,Yukon \nCanada \nY1A 2C6 \n \nPlease visit our website at:  http://www.education.gov.yk.ca/\n    \n  \n    \n \n  "],
          "_version_":1533049305513852928}]
    }}
  </code></pre>
  
  <p>I see that the field content has a number of occurrences of word <code>PDF</code>.</p>
  
  <p>Why I am getting no result with the following query, when there is a field name <code>content</code> and it contains <code>PDF</code> inside?:</p>
  
  <pre><code>select?q=*:*&amp;fq=content:PDF
  
  {
    "responseHeader":{
      "status":0,
      "QTime":4,
      "params":{
        "q":"*:*",
        "indent":"on",
        "fq":"content:PDF",
        "rows":"50",
        "wt":"json"}},
    "response":{"numFound":0,"start":0,"docs":[]
    }}
  </code></pre>
  
  <p>When I query using different field, for example <code>title</code>, then I have the right result:</p>
  
  <pre><code>select?q=*:*&amp;fq=title:PDF
  
  {
    "responseHeader":{
      "status":0,
      "QTime":3,
      "params":{
        "q":"*:*",
        "indent":"on",
        "fq":"title:PDF",
        "rows":"50",
        "wt":"json"}},
    "response":{"numFound":1,"start":0,"docs":[
        {
          "links":["http://www.education.gov.yk.ca/"],
          "id":"doc1",
          "last_modified":"2008-06-04T22:47:36Z",
          "title":[" PDF Test Page"],
          "content_type":["application/pdf"],
          "author":"Yukon Canada Yukon Department of Education",
          "author_s":"Yukon Canada Yukon Department of Education",
          "content":[" \n \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  \n  PDF Test Page \n \n    \n  \n \nPDF Test File \n \nCongratulations, your computer is equipped with a PDF (Portable Document Format) \nreader!  You should be able to view any of the PDF documents and forms available on \nour site.  PDF forms are indicated by these icons:   or  .   \n \nYukon Department of Education \nBox 2703 \nWhitehorse,Yukon \nCanada \nY1A 2C6 \n \nPlease visit our website at:  http://www.education.gov.yk.ca/\n    \n  \n    \n \n  "],
          "_version_":1533049305513852928}]
    }}
  </code></pre>